Preheat oven to 400°F with a rack in the center.

Slice baguette on the bias into ¼-inch thick slices and brush with the olive oil. Place onto a baking sheet. Bake until lightly toasted, flipping once, about 10-15 minutes.

Meanwhile, melt the butter over medium heat in a wide frying pan.

Add the shallot and garlic and cook, stirring once in a while, until beginning to soften, about 1 minute.

Add the mushrooms, salt, and pepper, and stir to coat with butter.

Cook, stirring occasionally, until the mushrooms have given off their liquid, browned slightly, and reduced to about half their original volume, 5 to 10 minutes.

If using sherry, port, madeira, or marsala, pour it into the pan and simmer until almost completely reduced.

If using brandy, you'll flambé it. Remove the pan from the heat and pour in the brandy from a measuring cup. (Don't pour directly from the bottle despite what you may have seen in the movies.) Very carefully light a long match and touch the surface of the mushroom mixture to ignite the brandy. Or, if you're cooking with gas, you can tip the pan away from you into the burner's flame until the brandy ignites. I find this method maybe a little too entertaining. Stand back until the flame dies out. Return the pan to medium heat.

Add the cream and stir to combine. Simmer until the cream has thickened enough to cling to the mushrooms, a minute or two.

Turn off the heat and stir in the Parmesan cheese and parsley.

Spoon mushrooms onto toasted baguette slices and serve.