Step 1

Grease an 8" baking pan with oil and line the bottom with a round of parchment paper.

Step 2

Arrange the plums in concentric overlapping circles on top of the parchment paper and sprinkle with 1 tablespoon of the sugar.

Step 3

Preheat the oven to 350°F.

Step 4

In a medium bowl, sift together the chestnut flour, sweet rice flour, oat flour, xanthan gum, baking soda, baking powder and salt. Set aside.

Step 5

In the bowl of a stand mixer, cream together the butter and remaining 3/4 cups sugar over medium speed until light and fluffy, 3-4 minutes.

Step 6

With the mixer on low-speed, add the eggs one at a time, mixing after each one.

Step 7

Add the vanilla extract, mixing until just combined.

Step 8

Keeping the speed on low, slowly add the dry ingredients in two batches, adding the milk in between, mixing until just combined.

Step 9

Pour the batter over the plums and use a spatula to smooth it out.

Step 10

Bake for 50-60 minutes, or until the center bounces back when touched and a toothpick inserted in the center comes out clean or with just a few moist crumbs. Place pan on a wire rack to cool completely (I left mine overnight).

Step 11

When completely cool, use a thin knife to loosen the edges of the cake. With a plate or second wire rack on top, invert the cake, giving it a few taps as needed to release it from the pan. Carefully peel off the parchment paper.

Step 12

Just before serving, brush the top with a little bit of honey to glisten up the fruit. Slice and serve as is, or with a scoop of vanilla ice cream.