In a heavy skillet, melt 1 tablespoon of butter. Add sliced onions and mushrooms. Season with salt and pepper. Cook on medium heat until browned and caramelized.
Add sherry and continue cooking until sherry has evaporated. Stir in fresh thyme.
Butter one side of each slice of bread. On the non-buttered side, spread a thin layer of fig jam or chutney on only one slice. Layer 1/4 each of the mushroom-onion mix, fresh spinach, and Manchego cheese. Top with the second piece of bread, buttered side out.
Place the sandwich butter side down in a panini maker or *heated skillet. Cook sandwich 7 to 10 minutes or until the bread is browned and the cheese is melted.
You can use a hot skillet if you don't have a panini maker. After placing the sandwich in the pan, top it with another pan to lightly press the sandwich.I used slightly thin sourdough bread. You can use any mild tasting bread.
This recipe was calculated using the exact brands and measurements I used to make this recipe. If you are following a strict diet please note changing anything will cause the nutritional info to change. My calculations are intended as a guide only.