To prepare a tarte tatin w oatmeal crust baked goods recipe, first you will need to prepare the crust. Preheat the oven to 375 degrees F (190 degrees C) and grease and flour two 9-inch tart pans. Set aside. Melt the butter in the microwave in 30 second increments, stirring constantly, until it's melted and smooth. Add the sugar and beat until the mixture is light and fluffy, about 2 minutes. Pour the batter into the prepared tart shells and bake for 20 to 25 minutes or until they are golden brown. Remove from oven and let cool before serving.