Preheat the oven to 400°F. Grease a 9 inch pie plate.
Heat a large skillet over medium-high heat. Add the ground beef and onion. Cook until the beef is browned and the onion is tender. Drain any excess grease.
Add the taco seasoning to the cooked beef.
Evenly spread the beef across the bottom of the prepared pie plate.
Sprinkle the cheddar cheese over the beef.
In a medium bowl, whisk together the baking mix, milk and eggs until smooth.
Pour the batter over the beef and cheese in the pie plate.
Bake uncovered for 25 to 30 minutes, until the top is golden brown and a knife inserted in the center comes out clean.
Allow the pie to sit for 5 to 10 minutes before slicing and serving with your favorite taco toppings.
*Nutritional information is a calculated guesstimate. Please note that this can change with different brands and modifications you may make to the recipe. For the most accurate information, use a nutritional calculator with the exact brands and measurements you're using with each recipe.