Cook 8 slices bacon in a large skillet over medium heat, turning occasionally, until crisp, about 10 minutes; transfer to paper towels to drain. Lay 8 slices 1/2″-thick country-style white bread on a work surface and brush each slice with 1/2 tsp. olive oil. Turn bread oiled side down. Spread each slice with 1 Tbsp. barbecue sauce; top each of 4 slices with 1 slice of cheddar, then 2 slices of bacon, then another slice of cheddar. Top with remaining bread slices, keeping oiled side facing up. Heat a large skillet over medium heat. Place two sandwiches in pan and reduce heat to medium-low. Cook until golden, 3-4 minutes. Flip sandwiches to brown other side, 3-4 minutes longer. Repeat with remaining sandwiches.
photo credit Kimberly Hasselbrink