Preheat oven to 350 degrees. Use a 10- inch well seasoned cast-iron pan or clear glass pie pan (spray with cooking spray). TIP: You can also use parchment paper to lay down, then pour the butter; add the brown sugar.
PARCHMENT: Melt 1/4 cup butter and stir in 1/2 cup brown sugar until blended. Spread over parchment paper. CAST IRON OR PIE PLATE: Place 1/4 cup butter in a 10-in. cast-iron and heat butter until melted, about 5-7 minutes. Or, melt the butter in a clear glass pie pan. Add the brown sugar.
Arrange the drained (if using canned) peach slices on top of the brown sugar mixture.
For batter, in a large bowl, cream butter and sugar until light and fluffy. Beat in egg, vanilla, and almond extract. In another bowl, whisk flour, baking powder and salt; add to creamed mixture alternately with buttermilk, beating after each addition just until combined. Spread batter evenly over peaches.
Bake until a toothpick inserted in center comes out clean, 35-40 minutes. Cool 10 minutes. Run a knife blade around the edge of each cake to loosen it from the pan. Invert the cake onto a serving plate. Lightly tap the bottom of the pan to loosen the cake, then lift the pan.
Peel off the parchment paper (if using).
To make the whipping cream, pour into a medium bowl and whip until thick, about 2-3 minutes. Add the powdered sugar and vanilla and gently mix together for about 20-30 seconds.
Serve the upside down cake warm with a dab of whipped cream on top!