In a bowl, whisk together tomato sauce, ketchup, brown sugar, Worcestershire sauce, mustard, garlic powder, onion powder, and black pepper. Set aside.
Heat olive oil in a large pan over medium heat. Add onions and bell peppers and cook until soft, 5 to 6 minutes.
Add garlic and cook 1 minute until fragrant.
Add ground beef and cook until browned, breaking apart as it cooks. Drain excess grease.
Pour prepared sauce over beef and stir to combine. Reduce heat to low and simmer 15 minutes, stirring occasionally.
While beef simmers, whisk together half and half, cornstarch, onion powder, and garlic powder in a small saucepan.
Bring to a light boil over medium high heat, whisking constantly.
Reduce heat to low and gradually stir in grated cheese until melted.
Add diced green chiles and season with salt. Keep warm on low heat.
Toast brioche buns in a hot skillet until golden brown.
Spoon beef mixture onto bottom buns, top with queso and sliced jalapeños, then cap with top buns. Serve immediately.