Add the Jennie's All-Purpose Baking Mix to a deep bowl, and set aside.
Add the buttermilk, butter and eggs to a bowl or measuring cup. Beat with a fork to mix well. Pour into the bowl with the baking mix. Stir with a fork until just combined, and there are no visible traces of flour. Stir in the cheese and the Caramelized Onions. Rest the batter for 5 minutes.
Meanwhile, preheat the waffle iron. Drop spoonfuls of the batter onto the waffle iron, and cook
Jennie's All-Purpose Baking Mix:
Add the flour, sugar, baking powder, baking soda and salt to a large container. Cover and shake well to combine. Store in a cool, dry place for up to 1 month. Shake before each use to re-mix the ingredients.
Melt the butter in a deep skillet over medium-low heat. Add the onions. Stir to coat the onions with the butter. Cover and cook, stirring occasionally, until the onions are very tender, 20 to 25 minutes. Uncover the onions, and raise the heat to medium-high. Cook, stirring occasionally until the liquid mostly evaporates and the onions turn a deep golden color, about 10 minutes. Season with salt.