I was browsing through my cookbooks this weekend and found this great recipe. Making desserts from scratch isn't as much work as people make it out to be. Plus experimenting with some of these methods are interesting. I overcooked my bars, but other than that they were amazing!
From America's Test Kitchen Menu Cookbook
1 1/2 cups quick oats
1 1/2 cups light brown sugar, packed
3⁄4 cup all-purpose flour
1⁄2 teaspoon baking powder
1⁄4 teaspoon baking soda
1⁄8 teaspoon salt
12 tablespoons unsalted butter, melted and cooled
1⁄2 cup all-purpose flour
1⁄2 cup light brown sugar, packed
4 teaspoons instant espresso or 2 teaspoons instant coffee
1⁄2 teaspoon salt
3 cups semi-sweet chocolate chips
4 tablespoons unsalted butter
2 large eggs
Start with the crust and topping: Adjust oven rack to the middle position and heat the oven to 325 degrees. Line a 13x9 inch square baking pan with a parchment paper sling.
Whisk oats, brown sugar, flour, baking powder, baking soda, and salt together in a large bowl. Stir in the melted butter until combined. Reserve 1 1/4 cups of the oat mixture for the topping.
Sprinkle the remaining oat mixture into the prepared pan and press into an even layer with the bottom of a measuring cup. Bake the crust until light golden brown, about 8 minutes. Let the crust cool completely on a wire rack, about 1 hour.
For the filling: Whisk the flour, sugar, instant espresso, and salt together in a medium bowl. Melt the chocolate chips and butter together in a microwave, stirring often, 1 to 3 minutes. Transfer the chocolate mixture to a large bowl and let cool slightly. Whisk in the eggs until combined. Stir in the flour mixture until just incorporated.
Spread the filling evenly over the cooled crust and smooth the top. Sprinkle with the reserved oat topping. Bake the bars until a toothpick inserted into the center comes out with a few moist crumbs attached and the filling begins to pull away from the sides of the pan, 25 to 30 minutes, rotating the pan halfway through baking.
Let the bars cool completely in the pan, set on a wire rack, about 2 hours. Remove the bars from the pan using the foil, cut into squares, and serve.