Preheat the oven to 350° F. Grease 2 8-inch cake pans with nonstick spray and line with parchment paper.
Mix together all cake ingredients. Pour the batter into the prepared pans. Bake for 25-30 minutes until a toothpick comes out clean.
With a standing or handheld mixer, whip together the vegan butter, cream cheese, nut butter, lemon juice, and vanilla. In batches, sift in the powdered sweetener— alternating with the milk as needed until you reach your desired consistency.
When the cakes are done, cool completely before removing from the pan and stacking/filling them with the frosting.
