Preheat the oven to 350 degrees F. Line a cupcake pan with 12 cupcake liners. Line a baking sheet with parchment paper.
For the cake batter: Sift together the cake flour, baking powder, baking soda and salt in a large bowl. Mix in the granulated sugar, oats and cinnamon. Add the oil, buttermilk and eggs and mix until smooth and completely combined.
Pour the batter into the cupcake liners and bake until golden brown and risen, 8 to 10 minutes. Let cool completely before frosting.
For the apple compote filling: In a small skillet, bring the granulated sugar, cinnamon, apples and 2 tablespoons water to a simmer over medium heat and cook until the apples are soft, about 10 minutes. Set aside to cool completely.
For the oat crumble: In a small bowl, combine the oats, brown sugar, molasses, oil and cinnamon. Pour the mixture onto the prepared baking sheet and bake, checking every 2 minutes, until golden brown. Set aside to cool, and then crumble into pieces.
For the molasses frosting: In a medium mixing bowl using an electric mixer, cream the butter until smooth and light. Add the confectioners' sugar 1/4 cup at a time and mix until completely combined. Add the molasses and mix.
To assemble: Remove the center of each cupcake with a paring knife. Fill the center of each with some of the apple compote filling. Frost with the molasses frosting, and sprinkle with the oat crumble. Serve immediately, or store in airtight container for up to 2 days.
This recipe was created by a contestant during a cooking competition. It has not been tested for home use.