This was my first attempt at grilling acorn squash. But I got this idea in my head and decided to run with it.
You may want a bib, or at least an oversized napkin, to eat this sandwich. The Mascarpone cheese just oozes out, but it sure does taste good!
Cut squash in half lengthwise. No need to remove seeds at this point; they are much easier to remove after cooking.
Place in microwave-safe baking dish cut side down, with ½-inch of water. Cover loosely with waxed paper. Microwave on high power about 7-8 minutes, until squash meat is easily pierced with fork. Do not overcook to the point of mushiness; squash should still be firm. Let squash cool enough to handle.
Scoop seeds out of squash and slice crosswise into ½” thick slices. Remove peeling by running a thin sharp knife along outer edge. Pat dry with paper towels.
Heat a ridged grill pan on high heat. Brush squash slices with the butter. Grill squash a couple of minutes on each side, basting with butter. When done, remove to plate and keep warm.
Make filling: Combine the softened Mascarpone with the maple syrup until totally smooth. Spread the cheese on two of the bread slices.
Top the cheese with slices of the grilled acorn squash. Season with salt and pepper if desired. Place 2 slices of bacon on top. Drizzle a little maple syrup over all if desired. Top with watercress or lettuce leaves, and remaining bread.
If you feel like it, you can put these sandwiches in a Panini press, but they are just as good without that.