Prep. Preheat oven to 350 F.
Saute. In a large skillet, add 1 tablespoon vegetable oil (1 tablespoon) and saute the onion (1 cup) and bell pepper (1). Cook until soft (about 7 minutes). Add garlic (2) and cook until fragrant (about 1-2 minutes). Add the beef (1 pound) and cook until no longer pink, breaking the meat into small pieces with the back of your spoon as it browns. Tilt your pan to the side, and push meat and veggies to the opposite side, allowing excess grease to pool toward the titled side. Use paper towels and a set of tongs to soak up the pooled grease.
Toast + simmer. Add the chili powder (2 tablespoons), cumin (2 teaspoons), and oregano (1 tablespoon), and toast until fragrant, about 2 minutes. Add all remaining casserole ingredients and simmer uncovered over medium-low heat for 20 minutes.
Topping. Meanwhile, in a medium bowl, combine the almond flour (2 1/2 cups), psyllium husk (1/4 cup), Swerve or Lakanto (2 tablespoons), baking powder (4 teaspoons), and salt (1 teaspoon). Add the water (3/4 cup), corn extract (2 teaspoons), and whisked eggs (2). Stir to combine. Use a large spoon to drop the batter over the top of your filling, then spread evenly using damp fingers. Sprinkle shredded cheese (1/2 cup) over the top.
Bake pie in a preheated oven for 25 minutes. Allow it to cool slightly before dishing up. Top casserole slices with sliced green onions, sour cream, and tomatoes. Enjoy!