Preheat the oven to 350° Fahrenheit. Prep a 9x13 pan: grease the pan, then line with parchment paper and grease the parchment paper. In a large bowl, using an electric mixer, cream together the butter, brown sugar, and white sugar until lighter and fluffy. Add in the eggs, and vanilla and blend to combine.

In a separate smaller bowl, whisk together the flour, almond meal, baking powder, and salt. Pour the dry ingredients into the first bowl and stir to fully combine. Add in the chopped walnuts (or a mix of other fun add-ins!) and stir until evenly distributed. Pour the mixture into the prepped pan and bake for 30 minutes or until top and edges are golden brown. Let cool slightly before serving. These can last days in an airtight container, but they may be gone pretty quickly!