These brown butter toffee blondies are thick, chewy bars with toasted butter, brown sugar and bits of chocolate-covered toffee. Stir the batter together by hand, spread it in a 9-by-13-inch pan and bake at 350°F (175°C) for about 35 minutes.
Browning the butter is the extra step that gives these blondies their nutty flavor. These Heath bar blondies use both bread flour and all-purpose flour, with crushed chocolate-covered toffee folded through the batter. The recipe makes 12 generous bars, or you can cut them smaller for a dessert tray.
This is a conventional oven recipe. Find it in our oven recipes collection, and plan for cooling time as well as baking time. Warm blondies are soft; letting the pan cool makes them much easier to cut.
Ingredients and substitutions
The recipe card below has the exact quantities. A few ingredient details make a difference here:
Salted butter: Start with 1½ cups, or 3 sticks, measured before browning. Some water evaporates as the butter cooks. Use the resulting browned butter, including the toasted bits, without topping it back up to 1½ cups.
Brown sugar: This is the main sweetener and gives the bars their butterscotch flavor. Break up any hard lumps before mixing so they do not remain in the batter.
Bread flour and all-purpose flour: Use 1½ cups of each. The bread flour contributes chew; this recipe uses an equal amount of all-purpose flour. Spoon the flour into the measuring cups and level it off rather than scooping and packing it down.
Eggs, vanilla, baking powder and salt: Use 3 large eggs. Mix the baking powder and salt through the flours before adding them to the wet ingredients so they are evenly distributed.
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Chocolate-covered toffee: Measure 1½ cups of chopped or crushed Heath bars. Use small, uneven pieces rather than grinding everything to powder. Bag sizes vary, so measure the toffee instead of assuming one bag is the right amount.
How to make brown butter toffee blondies
1. Brown the butter, then let it cool
Cut the butter into evenly sized pieces and melt it in a saucepan over medium heat. A light-colored pan makes the brown bits easier to see. Stir frequently, scraping along the bottom, as the butter foams and the milk solids turn golden brown. Allow about 10 to 15 minutes, using the color and nutty aroma as your guide.
As soon as the solids are golden to amber brown, pour the butter into a large heatproof mixing bowl, scraping in the browned bits. This stops the hot pan from continuing to darken them. Let the butter cool until warm, not hot, before adding the eggs. If the solids are black or the butter smells acrid, start again; burnt butter will carry that flavor into the bars.
2. Prepare the oven and pan
Preheat a conventional oven to 350°F (175°C). Grease a 9-by-13-inch baking pan, or line it with parchment for easier removal. Do not squeeze the full batch into an 8- or 9-inch square pan: the thicker batter needs a different baking time.
3. Mix the batter by hand
Stir the brown sugar into the warm browned butter, then stir in the vanilla. Add the eggs one at a time, mixing after each addition. In another bowl, combine both flours, baking powder and salt. Fold the dry ingredients into the wet mixture just until the flour disappears, then fold in the toffee. The batter will be thick.
4. Bake and cool
Spread the batter evenly into the corners of the prepared pan. Bake for about 35 minutes, until the edges are set and a toothpick inserted into the center comes out mostly clean, with a few moist crumbs rather than wet batter. A streak of melted chocolate from the Heath pieces is different from uncooked batter; test another spot if you hit a piece.
Cool the blondies in the pan for about 30 minutes before cutting. For neat slices, let them cool completely. Cut into 12 large bars with a sharp knife, wiping the blade between cuts.
Troubleshooting
Dry or tough bars: Too much flour, overmixing after the flour goes in and overbaking can all make blondies firmer. Measure the flour lightly, stop mixing once it is incorporated and check the center instead of waiting for every crumb on the toothpick to disappear.
A raw center with firm edges: Confirm the pan is 9 by 13 inches and spread the batter evenly. Continue baking if the toothpick brings up wet batter. Cooling firms up baked blondies, but it does not finish cooking raw batter.
Bars that crumble when cut: Give them more time to cool before lifting or slicing. The 12-serving yield makes large bars; smaller squares are easier to arrange on a cookie tray.
Brown Butter Toffee Blondies
Thick brown butter toffee blondies with brown sugar and chocolate-covered Heath pieces. Mix by hand and bake in a 9-by-13-inch pan at 350°F (175°C).
Ingredients
- 1 1/2 cups salted butter (3 sticks)
- 3 cups brown sugar
- 3 large eggs
- 1 tablespoon vanilla extract
- 1 & 1/2 cups bread flour
- 1 & 1/2 cups all-purpose flour
- 1 tablespoon baking powder
- 1 teaspoon salt
- 1 & 1/2 cups medium ground Heath chunks
Instructions
- Cut the butter into evenly sized pieces. Melt in a saucepan over medium heat, stirring frequently and scraping the bottom as the butter foams. Cook until the milk solids are golden to amber brown and smell nutty, about 10 to 15 minutes. Immediately pour the butter into a large heatproof mixing bowl, including the browned bits. Let it cool until warm, not hot, before adding the eggs.
- Preheat a conventional oven to 350°F (175°C). Grease a 9-by-13-inch baking pan, or line it with parchment paper.
- Stir the brown sugar into the warm browned butter until combined, then stir in the vanilla. Add the eggs one at a time, stirring after each addition. In a separate bowl, combine the bread flour, all-purpose flour, baking powder and salt. Fold the dry ingredients into the wet ingredients just until no dry flour remains.
- Fold in the Heath chunks. Spread the thick batter evenly in the prepared pan, including the corners.
- Bake for about 35 minutes, until the edges are set and a toothpick inserted into the center comes out mostly clean, with a few moist crumbs and no wet batter. If the toothpick hits melted chocolate, check another spot.
- Cool in the pan for about 30 minutes before cutting into 12 large bars. For neater slices, let the blondies cool completely before lifting or cutting.
Notes
Measure the 1 1/2 cups of butter before browning. Use the browned butter and toasted milk solids without adding extra butter or water to replace what evaporated. If the solids turn black or smell burnt, start again.
Measure 1 1/2 cups of crushed Heath pieces rather than using an unspecified bag size. Spoon the flours into measuring cups and level them without packing.
The 30 minutes of additional time is an approximate cooling allowance; a hot pan may need longer to cool fully for clean slices. Allow the browned butter to cool until warm before adding eggs.
Store cooled blondies in an airtight container at room temperature for up to 4 days, or wrap and freeze for longer storage.
Storage and serving
Once completely cool, store the blondies in an airtight container at room temperature for up to 4 days. For longer storage, wrap individual bars and freeze them in an airtight freezer container. Thaw them while still wrapped to help keep them from drying out.
Serve them plain, or add a scoop of vanilla ice cream just before serving. For another dessert you can slice and share, try the Instant Pot chocolate chip cookie cake, or browse the dessert recipes.
Frequently asked questions
Do I measure the butter before or after browning?
Before. Start with the full 1½ cups of salted butter listed in the recipe. This recipe already calls for browning it; do not add extra butter or water to replace what evaporates.
Can I use only all-purpose flour?
This recipe uses equal amounts of bread flour and all-purpose flour. An all-purpose-only batch may have a different texture, and that variation has not been verified for this recipe. Use both flours for the recipe as written.
Can I make these in an air fryer?
This full batch is written for a conventional oven and a 9-by-13-inch pan. An air fryer version would need its own smaller-pan quantities and cooking checks, so use the oven directions for this recipe.
Are these blondies keto or gluten-free?
No. They contain brown sugar, wheat flour and toffee candy. Almond flour, coconut flour and sugar substitutes are not direct swaps for the ingredients in this formula.