Preheat oven to 375 degrees.
Slice the tops from the bell peppers and reserve them.
Remove seeds and membranes from the inside of each pepper.
Carefully carve simple jack o lantern faces into the peppers.
Heat olive oil in a large skillet over medium heat.
Add onion and garlic.
Cook for 2 to 3 minutes until fragrant and softened.
Add ground beef.
Season with garlic powder, onion powder, paprika, cumin, Cavender's Greek Seasoning, and black pepper.
Cook until browned.
Drain excess grease if needed.
Add prepared Spanish rice to the skillet.
Mix thoroughly until combined.
Fold in 1 cup cheddar cheese.
Remove from heat.
Stand the peppers upright in a baking dish.
Fill each pepper generously with the beef and rice mixture.
Top each pepper with remaining cheddar cheese.
Place the pepper tops back on.
Add a small splash of water to the bottom of the baking dish.
Cover loosely with aluminum foil.
Bake for 35 minutes.
Remove the foil and bake for another 10 to 15 minutes until the peppers soften and the cheese melts.
Let the peppers cool for 5 minutes before serving.
Serve warm with the tops slightly tilted for the jack o lantern effect.