Using a silicone pastry brush, brush melted butter on the top side of each slice of bread. Flip 4 of the slices over, and layer with ¼ cup shredded cheese, 6 jalapeño slices, 2 turkey slices, 2 strips bacon, and sliced avocado. Top with remaining bread slices with the buttered side up.
Preheat a large non-stick skillet over medium-low heat for 2 minutes. Put 2 sandwiches in the pan, and lightly press a round cake pan on top of the sandwiches to weight them down. Leave the cake pan on top of the sandwiches and cook until the first side is nice and golden brown, about 4-5 minutes. Remove the cake pan, flip the sandwiches over, and again press lightly with the cake pan. Cook until golden brown, about 2-3 minutes.
Move the sandwiches to a cutting board, and slice on the diagonal. Repeat with the remaining 2 sandwiches and serve immediately.
*** When you flip the grilled cheese the cake pan will be very hot! Please use oven mitts when handling it!