Slow-Cooked Cornbread and Sausage Strata

In a large skillet, cook the sausage with chopped onions over medium heat, stirring to break up the sausage, until fully cooked.
Drain and set aside.
In a large mixing bowl, combine the flour, cornmeal, sugar, baking powder, baking soda, and salt.
In a separate medium bowl, whisk together the eggs, milk, and melted butter.
Pour the egg mixture into the dry ingredients, stirring just until combined.
Spray a 2-quart slow cooker with nonstick baking spray.
Spread half of the batter into the slow cooker, then layer with half of the cooked sausage and half of the shredded cheese.
Repeat the layers with the remaining batter, sausage, and cheese.
Cover and cook on high for 2½ to 3½ hours, or until the cornbread is set and a toothpick inserted in the center comes out clean.
Spoon out portions directly from the slow cooker and serve warm.