Ingredients:
- Toasted Oat Crust
- 4 tablespoons unsalted butter, softened
- 3 tablespoons of light brown sugar
- 1 and 1/2 tablespoon sugar
- 1 large egg
- 3/4 cup rolled oats
- 1/4 cup flour
- 1/2 teaspoon kosher salt
- A pinch of kosher salt
- Gooey Butter Filling
- 1 cup sugar
- 1/2 cup (packed) light brown sugar
- 2 tablespoons milk powder
- 1 teaspoon corn powder
- 1/2 teaspoon kosher salt
- 1 and 1/2 sticks unsalted butter, melted
- 1 teaspoon vanilla extract
- 6 large egg yolks
- Confectioners’ sugar, to finish
Instructions:
- Heat oven to 350 degrees F. Pan-spray an 8 x 8-inch square baking dish.
- Toasted Oat Crust: In a large bowl, mix together the butter, brown sugar, and sugar with a spatula until well combined. Mix in the egg and stir until well combined, scraping down the sides of the bowl as you go. dd the oats, flour, salt, and baking powder, and mix just until combined. Pour this mixture into the greased baking dish and use a spatula to evenly spread the mixture, fully covering the dish’s bottom.
- Bake at 350 degrees F until edges of the crust are golden brown, about 20 minutes. Cool at room temperature for 10 minutes. Leave the oven on.
- Gooey Butter Filling: In a large bowl, whisk together the sugar, brown sugar, milk powder, corn powder, and salt. Whisk in the melted butter, vanilla, and egg yolks and stir until smooth. Try not to aerate the batter; mix slowly and gently. Pour this mixture on top of the oat crust, spreading evenly to all sides of the baking dish, covering the bottom layer entirely.
- Bake at 350 degrees F until the top and edges are golden brown and the bulls-eye center is still a bit jiggly, about 20 minutes.
- Remove from oven and ideally transfer the pan to an empty freezer to cool completely. This will cool down your first bite and also ensures that all the steam pockets subside. The result is a dense and gooey bar cookie, which is also much easier to portion when frozen.
- Cut into 12 squares. Dust with confectioners’ sugar before serving, if desired. Store in an airtight container or plastic wrapped on the counter for up to 5 days or in the fridge for up to 2 weeks.