Lay out 4 of your 8 bread slices and press your Halloween cookie cutter into the center of each one. Gently pop out the cutout piece and set both the cutout shape and the bread with the hole aside separately.
Spread softened butter evenly across one side of all 8 pieces, including the small cutout shapes. This step is what gives every piece that golden, crisp finish once it hits the pan.
Heat your griddle or skillet over medium heat and place the whole slices along with the cutout shapes butter-side down. Let them cook for about 3 minutes, or until lightly golden on that first side.
Flip the 4 whole slices of bread and place a slice of cheddar on top of each one. Set the matching cutout-holed slice over the cheese, buttered side facing up, so the spooky shape peeks through.
Cook the assembled sandwiches for another 2 to 3 minutes, until the bottom is golden and the cheese is fully melted. Press the little cutout shapes back into their holes as a fun garnish before serving warm.