Strawberry Upside-Down Cake

Ingredients

• 11 tablespoons unsalted butter, at room temperature, divided
• 3 tablespoons plus ½ cup brown sugar
• 1 quart strawberries, hulled and thinly sliced
• ⅔ cup whole wheat flour
• ⅔ cup all-purpose flour
• 1 teaspoon cinnamon
• ¾ teaspoon baking powder
• ¼ teaspoon baking soda
• Pinch of kosher salt
• 1 large egg
• 1 teaspoon vanilla extract
• ⅔ cup Greek yogurt