Slice the onions into thin strips. Heat a saute pan to medium-high heat. Add the butter into the pan and heat until butter is melting. Add the sliced onions. Season with the thyme, rosemary, brown sugar, salt and pepper. Let the onions saute until tender and then remove from heat and let rest while you assemble the sandwiches.
Heat a flat griddle to medium heat. Add some extra butter to the pan and let it melt a little. Place 4 slices of bread onto the griddle pan. Add one slice of cheddar cheese and provolone cheese. Add a spoonful of sliced onions. Add a top to the sandwiches. Let cook until the cheese starts to melt and is golden brown. Flip the sandwiches and sprinkle with the Garlic Seasoning Spread and cook on the other side. Transfer to a plate and serve warm with soup of choice.