Preheat the oven to 350°F. Line an 8x8" glass baking pan with parchment paper.
Place the butter and maple sugar in a large mixing bowl. Use hand-held beaters to cream the butter and sugar together until they are fluffy and light.
Add the maple syrup and egg. Beat until the mixture is smooth.
Stir in the flour, baking powder, extract, and oats. Stir until everything is combined.
Spread the mixture into the 8x8" baking pan.
Bake for 30-35 minutes. The center of the bars should be set and the top should be golden brown.
Allow the bars to cool on a wire rack before slicing and serving them. You can slice and serve them when they are still slightly warm, however, they may be a little crumbly. You can also garnish the bars with flakey sea salt and maple cream if you would like!
Store leftovers in an airtight container at room temperature.