Place the cucumber spirals in a large jar or bowl.
In another large bowl or measuring cup, whisk together the vinegar, salt, dill and hot water. Stir until the salt dissolves. Let the mixture cool. Once cool. pour it over the cucumber spirals. Add the garlic and pepper flakes. Make sure the spirals are all submerged in the liquid. Refrigerate overnight, shaking or stirring once or twice. These stay great for about a week!
Heat a large skillet over medium heat. Spread the outsides of the bread with the softened butter. Top one side with 1 ounce grated cheese, then about 1/4 cup pimento cheese. Spread it out gently with a spoon - it won't be even, but just kind of spread it around! Top with 1/2 cup arugula, a sprinkling of chives and then another ounce of grated cheese and other slice of bread. Repeat with remaining bread and ingredients.
Cook the sandwich in the skillet until the cheese is melted and bubbly and the bread is golden brown. Be sure to cool slowly so the center of the pimento cheese gets melty and warm! Serve immediately with the pickle slaw and chives on top!