Before You Begin
Preheat and prepare your cookware as needed. Cooking times and results may vary depending on your equipment and ingredients.
Cook bacon until crisp and drain on paper towels. Chop sun-dried tomatoes and blot dry.
Spread pesto on one side of each bread slice.
On two slices, layer mozzarella, bacon, tomatoes, and provolone. Top with remaining bread, pesto side inward.
Spread butter or mayonnaise evenly on outer sides of sandwiches.
Heat skillet over medium heat and cook sandwiches 3–4 minutes per side until bread is golden and cheese melts fully.
Remove from heat, rest briefly, slice, and serve warm.