In a small bowl mix butter and Dijon mustard until combined and smooth. Divide into fourths. Lay slices of bread out on your work surface. Butter top side of each slice with 1/4 of the butter mixture.

Prep your cheeses for quick sandwich assembly. Make two stacks, one slice of each cheese per stack, with american in the middle of each stack. Because american melts the easiest of the three putting it in the middle helps blend and bind all the cheeses while cooking.

Heat a nonstick skillet over medium low heat for a couple minutes. Working one sandwich at a time, place first slice of bread butter side down in skillet. Place stack of cheeses on top, pepper jack on bottom so it is closest to the heat first. This is because it is the slowest of the three to melt. Then place second slice of bread on top of cheeses, butter side up.

Place a lid on your skillet for 1 minute. Remove lid, cook 1 minute more. Lift corner of bread with a spatula to see how toasted it is. You want a golden brown color. On my stove this usually takes 2-4 minutes, including time with lid on.

When golden brown carefully flip sandwich with spatula. Press down top gently with back of spatula to squish the halves together. Cook another 2-4 minutes or until golden brown on second side.

Flip top side back down for a quick reheat (only about 20 seconds). Transfer to plate, let rest for 2 minutes for cheeses to set a little. Repeat cooking steps for second sandwich.

Once rested cut on the diagonal to display all that ooey gooey awesomeness, serve with a soup that begs you to dip something in it and enjoy. ;)