Rhubarb Maple Upside Down Cake - cooking recipe

Ingredients

4 tablespoons unsalted butter
3/4 cup brown sugar
3 cups diced rhubarb, cut in 1/4 inch dice
2 tablespoons granulated sugar
1 cup granulated sugar
1/2 cup unsalted butter, softened
2 eggs, separated
1 teaspoon vanilla extract
1 1/2 cups all-purpose flour
1/2 teaspoon salt
2 teaspoons baking powder
6 tablespoons milk
2 tablespoons maple syrup
1/4 teaspoon cream of tartar

Preparation

Preheat oven to 325 F. Generously butter a 9-in. round cake pan (do not use a springform pan as the mixture will leak- trust me). Melt 4 tbsp. unsalted butter over low heat. Stir in the brown sugar. Pour into cake pan and distribute evenly across the bottom of the pan. Sprinkle rhubarb with 2 Tbsp granulated sugar and toss. Place in pan on top of brown sugar mixture. Spread evenly and set aside.
Using an electric mixer, cream softened butter and 1 c. granulated sugar on medium speed until light and fluffy. Add egg yolks, one at a time, scraping down the sides of the bowl after each addition. Beat in vanilla extract.
In a separate bowl, mix the flour, salt and baking powder. Add 1/3 of the flour mixture to the batter in the mixer bowl on slow speed, scraping down the sides and mixing until dry ingredients are incorporated. Add half of the milk-syrup mixture. Continue alternating additions of dry ingredients and milk-syrup mixture, ending with the flour mix.
In a separate bowl, whip egg whites with cream of tartar until stiff peaks form. Fold egg whites into batter in small amounts until well-incorporated. Pour batter into pan on top of rhubarb.
Bake at 325 degrees 40-50 minutes or until the surface springs back to the touch. Let cool for 5 to 10 minutes. Run a table knife around the edges and invert onto a cooling rack. Serve either warm or at room temperature.
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