Combine wine, shallots, tomato paste, stock, and thyme in a pan over medium-high heat.

Bring to a boil.

Cook until reduced about half and reduction no longer smells overly alcoholic.

Strain the wine and stock mixture through a sieve over a bowl; discard solids (optional - if you leave shallots in there will be some texture, and sauce won't be smooth, but its great for dipping.)

Whisk in 5 teaspoons butter, 1 teaspoon at a time, stirring until butter melts.

In a small bowl, whisk cornstarch with warm water to create a slurry. (optional, to thicken sauce).

Add slurry to sauce by bringing to a boil and whisking in vigorously.

When sauce has thickened and reduced, it is ready to serve.

Shred cheeses and add to a bowl, toss together to mix well.

Generously slather one side of each slice of bread with mayonnaise.

Add one slice, mayonnaise side down, in a cold pan on the stove.

Layer cheese on top of bread and top with second slice, mayonnaise side up (the mayonnaise helps the bread crisp, so you want it facing out so it can cook off and crisp up.)

Turn heat on to medium, and let cheese start to melt as pan heats up, about 5 minutes.

When cheese has just started melting, and the bottom side is golden brown, flip to other side and cook another 5 minutes.

Watch to make sure pan doesn't get too hot.

Flip sandwich occasionally until cheese is soft and melted.

When grilled cheese has melted, remove from pan and slice in half.

Spoon red wine sauce over sandwich or serve alongside in a bowl for dipping.

Enjoy!