Preheat the Oven: Preheat oven to 425°F. Line a rimmed baking sheet with parchment paper for easy cleanup.
Cook the Beef: In a large skillet over medium heat, heat olive oil. Add ground beef and cook, breaking it apart with a spatula, until browned and cooked through, about 5–6 minutes. Drain excess grease if needed.
Make the Sauce: In a medium bowl, whisk together tomato sauce, chopped chipotle peppers, adobo sauce, brown sugar, Worcestershire sauce, onion powder, garlic powder, cumin, chili powder, salt, and pepper until smooth.
Toast the Buns: Place hamburger buns cut side up on the prepared baking sheet. Spread lightly with butter. Bake for 5–7 minutes, or until golden brown and lightly crisp.
Simmer the Filling: Pour the chipotle sauce into the skillet with the cooked beef. Stir to combine and let simmer for 4–5 minutes, until the sauce thickens and clings to the meat. Remove from heat.
Assemble and Serve: Spoon the smoky beef mixture onto toasted buns and top each with 2 pickle slices. Serve hot and messy!