Crust and Topping
1 cup (3 ounces) quick-cooking oats (I used old-fashioned)
1 cup packed (7 ounces) light brown sugar
3/4 cup (3 3/4 ounces) all-purpose flour
1/4 teaspoon baking powder
1/4 teaspoon baking soda
1/8 teaspoon salt
8 tablespoons unsalted butter, melted and cooled
1/4 cup (1 1/4 ounces) all-purpose flour
1/4 cup packed (1 3/4 ounces) light brown sugar
2 teaspoons instant espresso powder or instant coffee powder
1/4 teaspoon salt
1 1/2 cups (9 ounces) semisweet chocolate chips
2 tablespoons unsalted butter
1 large egg
- Preheat oven to 325 degrees F. Line an 8 x 8 baking pan with foil and lightly spray with nonstick cooking spray.
- Crust and Topping: whisk together oats, brown sugar, flour, baking powder, baking soda and salt in a large bowl. Stir in melted butter until combined. Reserve 3/4 cup oat mixture for the topping. Spread the remaining oat mixture into prepared pan and pat into an even layer. Bake until light golden brown, about 8 minutes. Let crust cool completely on wire rack, about 1 hour.
- Filling: whisk together flour, brown sugar, espresso powder and salt in bowl.
- In the top half of a double boiler over hot water, melt chocolate chips and butter, stirring together until melted and combined. Cool slightly for several minutes. Whisk in egg until combined. Stir in flour mixture until just incorporated.
- Pour filling in an even layer over cooled crust. Sprinkle evenly with reserved oat topping. Bake until toothpick inserted in the center comes out with a few moist crumbs, 25 to 30 minutes, rotating pan halfway through baking.
- Let bars cool completely in pan on wire rack before cutting and serving.