Preheat oven to 350 degrees and coat an 8x4 loaf pan with nonstick spray, butter, or coconut oil.
You can also add parchment paper to ensure the cake comes out properly.Add all dry ingredients to a medium-sized bowl (almond flour, coconut flour, collagen, baking powder, and salt).
Whisk to combine.In a large bowl or stand mixer, add eggs and vanilla.
Beat on high for 1 minute until light and fluffy.
Add in sour cream, melted butter, and milk.
Beat on high for 30-45 seconds.Slowly add dry ingredients to wet ingredients in 2 to 3 batches.
Mix well until combined.
Let sit for 2 minutes.
Mix one more time on low speed.Pour batter into prepared pan and bake for 50-60 minutes until tops and edges are golden brown and a toothpick comes out clean when poked through the center.
Add additional baking time if needed.