To stuff mushrooms, gut the majority of the flesh from inside the mushroom with a spoon, leaving an empty cavity behind. Next, spoon the prepared stuffing inside the cavity so that a bulb of it emerges at the top. Evenly place the mushrooms on a baking sheet and bake.
To ensure the best product, choose a mushroom hefty enough to accommodate stuffing. Among the larger varieties, portobellos work well. Among smaller varieties, select white button varieties measuring roughly 2 1/2 inches across. Before anything else, wipe off any dirt from the mushrooms with a wet paper towel without washing them directly under water, as mushrooms absorb the excess liquid.
Stuffing options vary widely, and include such options as bacon, sausage, cream cheese, crab and vegetarian options, such as spinach. If a protein such as bacon is involved, it requires cooking prior to its introduction into the stuffing.
Before placing the stuffed mushrooms on the baking sheet, drizzle the vessel with olive oil or spritz it with non-fat cooking spray to avoid sticking. For most stuffed button and portobello recipes, 25 to 30 minutes in a 400 degree Fahrenheit oven is sufficient. After that time elapses, check to see that the bulb of stuffing atop the mushroom has turned golden brown and that the mushrooms themselves are tender.