Oat Milk Cinnamon Swirl Sheet Pan Pancakes

Name: Oat Milk Cinnamon Swirl Sheet Pan Pancakes
Ingredients: 4 tablespoons vegan unsalted butter, melted and cooled slightly; 1/3 cup vegan granulated sugar; 1 tablespoon fresh lemon juice (from 1/2 lemon); 1 1/2 teaspoons kosher salt; 2 1/4 cups plus 4 teaspoons oat milk; 1 tablespoon plus 1 teaspoon vanilla bean paste; 2 3/4 cups all-purpose flour (see Cook's Note); 1 tablespoon baking powder; 1/4 cup firmly-packed vegan light brown sugar; 2 teaspoons ground cinnamon; 1/2 cup vegan confectioners' sugar; Maple syrup, for serving, optional