Melt 1/2 tablespoon butter in a (10-12 ounce) microwave-safe mug with 3-4 peach slices and 1 tablespoon brown sugar for 30 seconds to 1 minute. In a bowl, whisk 1 tablespoon melted butter with 1 tablespoon brown sugar, the egg, and vanilla. Add the flour, oats, baking powder, and salt, stirring until just combined.Spoon the batter over the peaches in the mug. Do not stir. Place the remaining peach slices on top. Sprinkle with 1 tablespoon of brown sugar and a pinch of cinnamon. Add 1/2 a tablespoon of butter. Microwave on full power for 1 minute 45 seconds to 2 minutes (I always do 2 minutes). Serve with ice cream. ENJOY.