In a medium bowl, whisk together the eggs, whole milk, salt, black pepper, ground cumin, and smoked paprika until well combined.
Heat the olive oil in a large non-stick skillet over medium heat.
Add the diced red bell pepper, green bell pepper, and yellow onion to the skillet. Sauté for 5-6 minutes until the vegetables are softened.
Add the chopped spinach to the skillet and cook for an additional 1-2 minutes until wilted.
Pour the egg mixture over the sautéed vegetables in the skillet. Cook, stirring gently, until the eggs are fully scrambled and cooked through, about 4-5 minutes. Remove from heat.
Warm the flour tortillas in the microwave for 15 seconds to make them pliable.
Divide the scrambled egg and vegetable mixture evenly among the six tortillas, placing it in the center of each.
Sprinkle about 2 tablespoons of shredded cheddar cheese over the egg mixture on each tortilla.
Fold the sides of each tortilla inward, then roll tightly from the bottom up to form burritos.
Wrap each burrito tightly in aluminum foil or plastic wrap for freezing.
To reheat, remove the wrapping and microwave the burrito on a microwave-safe plate for 2-3 minutes, turning halfway through, until heated thoroughly. Alternatively, reheat in a 350°F (175°C) oven for 20 minutes.