- 8 tablespoons butter, softened
- ¾ cup sugar
- 2 large eggs, at room temperature
- 1½ cups flour
- 1½ teaspoons baking powder
- 1 teaspoon vanilla extract
- ¼ teaspoon salt
- ½ cup whole Greek yogurt, at room temperature
- 4 tablespoons cold butter
- 1 tablespoon lemon juice
- ¾ cup packed light brown sugar
- 6 plums, quartered
1. Place the softened butter in the bowl of a stand mixer fitted with a whisk attachment. While whipping on medium-high speed, add the sugar a little at a time until it is all incorporated. Add the eggs and whisk until smooth.
2. Remove the bowl from the stand mixer and stir in the flour, baking powder, vanilla extract, salt and yogurt, being careful not to over-mix.
3. Prepare a gas or charcoal grill for medium-hot grilling. Add the 4 tablespoons of cold butter to a 10½-inch cast iron pan on the grill. When the butter is melted, add the lemon and sugar and cook, stirring until the sugar is melted, about 2 minutes. Add the plums, stir, then pour the cake batter over the top.
4. Cover the skillet with foil and grill until the cake has set and the fruit begins to bubble, about 30 minutes. Carefully remove from the grill and allow the cake to cool for 10 minutes before serving.