Preheat oven to 350° F. Line a 9"x13" pan with foil, allowing it to hang over the sides (to be used as handles to remove the brownies from the pan later). Grease the pan and foil and set aside.
In a large bowl, combine oats, flour, brown sugar, and baking soda. Stir to combine.
Add melted butter and stir to combine, ensuring the butter coats all the ingredients. Reserve ¾ cup of the oat mixture to use later as topping. Press the remaining oat mixture into the bottom of the prepared pan.
Bake crust for 10 minutes. Crust will not brown, but will be puffed.
Combine dry ingredients (flour, baking powder, and salt) in a small bowl. Set aside.
In a large saucepan, melt chocolate and vegetable shortening over low heat. Remove from heat once smooth.
Add sugar, eggs, vanilla extract, and chocolate extract. Stir to combine. Add dry ingredients and stir just until incorporated.
Pour batter on top of baked crust and spread to cover/smooth the top. Sprinkle with the reserved oat mixture.
Bake 30-35 minutes, or until a toothpick inserted near the center comes out clean. When in doubt, err on the side of caution and pull them a little early rather than a little late. Fudgy brownies are SO much better than dry brownies!
Allow brownies to cool completely on a wire rack. Using the foil 'handles,' remove the brownies from the pan and cut as desired.
