To a food processor add the mayo, sage, roasted garlic cloves, olive oil, lemon juice, and lemon zest. Pulse a few times to combine the ingredients well. Transfer to a bowl; set aside.
Spread butter on both sides of 4 slices of bread. Place the skillet over a low-medium flame and brush the surface with butter.
Layer the bread slices in the pan to brown on one side for 1-2 minutes. Flip the slices adding more butter to the surface of the pan. Place 2 slices of cheese on each bread slice.
Quickly place the turkey breast on 2 slices of bread followed by the bacon on the other 2. Generously spread the sage mayo on the turkey then flip the bread with the bacon on top.
Allow the cheese to melt for about 30-45 seconds before flipping both sandwiches to melt the cheese on the other side for the same amount of time if needed. Remove the sandwiches from the pan and cut in half before serving.