Set your oven to broil. Place an oven rack in the upper third portion of the oven.
Line a sheet pan with parchment paper or aluminum foil. Lay out the six slices of bread on the pan.
Melt the butter in the microwave. Use a pastry brush to apply a light coating of melted butter on one side of each slice of bread.
Toast bread on both sides (about 2 minutes per side, watch closely so as not to burn) until both sides are toasted. One side of each slice of bread will be buttered and one side will not.
In a small bowl, mix together the mayonnaise with tarragon, garlic powder, lemon juice, salt and pepper.
For each sandwich, spread the first slice of bread (on the buttered side) with a thin layer of mayonnaise. Make sure to go all the way to the edges.
Layer on three slices of ham (for each sandwich).
Top with two slices of cheddar cheese (for each sandwich).
Top with two lettuce leaves (for each sandwich).
Spread a thin layer of the mayonnaise on BOTH sides of the middle slice of bread and place it on top of the lettuce.
Then top that second slice of bread with three slices of chicken (or turkey).
Top the chicken with one or two tomato slices and three slices of bacon.
Spread the remaining mayonnaise onto the final piece of bread (on the buttered side).
Place the final piece of bread on top of the bacon (for each sandwich).
Use a sharp knife to slice each sandwich into equal quarters.
Secure each triangle with a frilled toothpick. Serve immediately.