In a large bowl, whisk together the 1/2 cup butterooled brown butter and coconut sugar until smooth, about 3-5 minutes. Then, add the egg, egg yolk, vanilla, and maple syrup. Mix until creamy and well combined.
1/2 cup butter, 3/4 cups coconut sugar, 1 egg + 1 egg yolk, 2 tsp vanilla, 1 tbsp pure maple syrup