Place all carrot cake ingredients into a food processor and process until smooth.
Place all frosting ingredients (start with 1/3 cup oat milk) into a food processor and process until smooth. Add more oat milk if needed. The texture should be thick and smooth.
Line a square baking tin and scoop carrot cake in. Smooth with the back of a damp soon. Spread over frosting, garnish and set in the freezer for 1-2 hours
Remove from the freezer, slice and enjoy! Store in the fridge for 3-4 days