In the bowl of a stand mixer fitted with the paddle attachment, mix the coconut oil and sugars together until light and creamy, for about 2 minutes. Add the eggs and vanilla and mix for an additional minute until combined, scraping the sides of the bowl as necessary. Lower the speed of your mixer to low and alternate the flour and sour cream, beginning and ending with the flour. Mix until smooth. Spread the batter in the prepared pan and sprinkle the crumb mixture evenly on top.