Strawberry Rhubarb Upside Down Cake

Ingredients

3/4 cup butter, divided
1 cup light brown sugar, divided
1/2 cup sugar, divided
3/4 pound rhubarb, sliced 1/4-inch thick
1 cup hulled and halved strawberries 
1 3/4 cups all-purpose flour
1 teaspoon baking powder
1/2 teaspoon salt
2 large eggs
1/3 cup milk
1 tablespoon lemon juice
1 teaspoon grated lemon zest
1/2 teaspoon vanilla extract

Directions

1. Heat oven to 325°F. Spray an 8-inch square baking pan with nonstick cooking spray.
2. Melt 1/4 cup butter in oven, about 5 minutes. Sprinkle 1/2 cup brown sugar and 1/4 cup sugar over butter. Stir until well blended. Bake an additional 5 minutes or until bubbly.
3. Add strawberries uncut side down and rhubarb to pan.
4. In a large bowl, add flour, baking powder and salt. Stir until blended.
5. Using a hand mixer on medium speed, beat in remaining 1/2 cup butter, 1/2 cup brown sugar and 1/4 cup sugar, eggs, milk, lemon juice and zest and vanilla extract until blended, about 2 minutes.
6. Bake 55 to 60 minutes or until toothpick inserted in center comes out clean. Cool 15 minutes on cooling rack. Invert onto serving plate.