-
1
Heat a large skillet over med-high heat; add 4 tablespoons butter.
-
2
When it has melted, add the onions, sugar, salt, thyme, and black pepper.
-
3
Saute for 5 minutes, stirring the onions until they become soft, then turn the heat to low and cook the onions slowly, stirring occasionally, until they are very soft and browned, about 30 minutes.
-
4
Add the balsamic vinegar and turn the heat back to med-high.
-
5
Cook the onions until the vinegar has evaporated, about 1 minute.
-
6
Remove the pan from the heat and set aside.
-
7
Butter the baguette slices and lay them, buttered side down, on a work surface.
-
8
Spread some of the onion jam on the unbuttered side of half the baguettes, and season with salt and pepper if desired.
-
9
Top the onion jam with about 1 tablespoon of the grated cheese.
-
10
Top the cheese with a baguette slice, buttered side up.
-
11
Heat a panini maker or a large, nonstick skillet over medium heat.
-
12
Arrange 4 or 5 of the panini on the hot surface.
-
13
Close the lid of the panini maker or, if using, a skillet, weight the panini down with a smaller heavy skillet that fits inside the one you are cooking inches.
-
14
It should take about 2 minutes to cook the panini until brown in a panini maker.
-
15
If using a skillet, cook 2 minutes on the first side, 1-2 minutes on the second side.
-
16
Arrange the cooked panini on a platter.
-
17
Serve hot or at room temperature.
