Lemon Crumble Breakfast Cake

Name: Lemon Crumble Breakfast Cake
Prep time: 20 min
Cook time: 40 min
Total time: 1 h
Cuisine: American
Ingredients: 4 tablespoons unsalted butter, melted; ¾ cup all-purpose flour; ⅓ cup granulated sugar; 1 tablespoon fresh lemon juice; zest of 1 lemon; 2 cups all-purpose flour; ½ teaspoon salt; 2 teaspoons baking powder; ½ cup unsalted butter, room temperature; zest from 2 lemons (preferably organic); ¾ cup granulated sugar; 2 large eggs, room temperature; 1 ½ teaspoons vanilla bean paste; ½ cup buttermilk, well shaken (whole fat or whole milk mixed with 1 1/2 teaspoons vinegar); ¼ cup fresh lemon juice (about 2 lemons); powdered sugar for dusting if desired