Preheat oven to 350ºF. Spray a 9x13” baking pan with cooking spray. Line with parchment paper if you'd like it to come out cleanly.
Combine the crumbs, 1/2 cup pecans, flour, baking powder, and salt.
In a large bowl, cream the butter and the light brown sugar until fluffy. Slowly beat in the egg yolks, one at a time. Stir in the vanilla. Alternately add the milk and the crumb mixture while beating on low.
Beat the egg whites in a bowl until foamy. Add the sugar slowly, and beat to soft peaks. Fold into the crumb batter, and pour into the pan.
Bake for 35 minutes, or until a tester comes out clean. Cool in the pan on a wire rack.
Make the frosting:
Whip the butter alone in a stand mixer on medium for 2 minutes or until fluffy, almost white in appearance and lighter in texture.
Add the vanilla and cinnamon. Add the powdered sugar slowly, mixing between each addition.
Alternate the last bit of powdered sugar and the heavy cream, and whip the frosting on high for at least 2 minutes. If the buttercream is too thick after 2 tablespoons of heavy cream, add a third tablespoon.
Spread the frosting over the cooled cake. This makes just a thin layer of frosting. Double the frosting if you’d like a thick layer.
*1 cup whole pecans, crushedRefer to the article above for more tips and tricks.The calories shown are based on the cake being cut into 15 pieces, with 1 serving being 1 frosted slice of cake. Since different brands of ingredients have different nutritional information, the calories shown are just an estimate. **We are not dietitians and recommend you seek a nutritionist for exact nutritional information. The information in the nutrition box are calculated through a program and there is room for error. If you need an accurate count, I recommend running the ingredients through your favorite nutrition calculator.**