4-5portobello mushrooms, about 3" diameter or fewer if larger
2TablespoonsBalsamic, Italian or French vinaigrette, for marinating *see Note 1 below
Filling:
1teaspoonbutter
1teaspoongarlic, minced
1-2teaspoonsshallot, minced (or onion)
1/2cupheavy whipping cream, 35% b.f.
2Tablespoonsgoat cheese, crumbled
2TablespoonsParmesan cheese, grated
4cupsbaby spinach
Salt and freshly ground pepper
Panko topping:
2teaspoonsbutter, melted
3Tablespoonspanko
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Instructions
Clean the portobello mushrooms: Remove and discard the stem if there is one by twisting it. Use the edge of a spoon to scrape out the brown gills on the underside of the mushrooms and discard. Use a damp paper towel to gently wipe the topside and underside of the mushrooms.
Place the cleaned mushrooms into a shallow bowl and drizzle with balsamic, Italian or French vinaigrette. (If you don't have ready-made vinaigrette, you can simply combine a bit of olive oil (about 1 tablespoon) with a splash of balsamic vinegar (about 1 teaspoon), along with a bit of salt and pepper.) Toss the mushrooms around in the marinade a bit, then place onto a baking sheet to marinate while the oven preheats.
Preheat the oven to 400F. (non-convection)
When the oven is preheated, pop the mushrooms into the oven for 7 minutes.
Meanwhile, start the filling by melting the butter in a skillet on the stove-top over medium heat. Add the garlic and shallot and cook, stirring, until fragrant, about 45-60 seconds. Add the cream to the skillet and bring to a simmer. Reduce heat slightly and allow to simmer until it is reduced by half.
When the mushrooms have baked for 7 minutes, remove from the oven and use a paper towel to blot the liquid that has collected in the cup of the mushroom (you can also use gloves and just tip the liquid out, if you prefer). Set aside until the filling is ready, leaving the oven set to 400F.
When the cream for the filling has reduced, stir in the goat cheese. Add the spinach and the Parmesan and cook, stirring, until the spinach is wilted. Generously season with salt and freshly ground pepper.
Use tongs to transfer the spinach to the mushrooms, then top up the mushroom "cup" with some of the liquid, until it is filled.
Make the panko topping by stirring together the melted butter and panko until moistened. Mound the panko topping on top of the mushroom filling, then return the mushrooms on the baking sheet to the oven and bake about 7-8 minutes more, or until the panko is golden.
Bake gill side up at 400F for about 7 minutes. Remove from oven and blot liquid out of "cup".
Remove from oven and let stand a couple of minutes before serving. to allow the filling to set a bit.
Notes
Be sure to read the information above this Recipe Card, for cooking tips, how to clean portobello mushrooms and step-by-step photos.