Need a veggie-packed breakfast to spice up your mornings? These easy stuffed breakfast mushrooms are it! Meaty portobello mushrooms make a base for veggies and an egg and are topped with feta cheese before baking in the oven.
Preheat your broiler on high. If your broiler has a temperature setting, set it to 400ºF.
Rinse mushrooms under cold running water to remove any dirt or debris. You can use a damp paper towel to wipe the tops if you'd prefer not to rinse them. Remove stems if your mushrooms have them.
Drizzle the mushrooms with just a touch of olive oil, salt, and pepper, using your hands to cover both sides.
Place mushrooms on baking tray and broil for about 5 minutes. Using tongs, flip each mushroom over and broil on the other side for 5 minutes. (There will be some liquid accumulation.) Set mushrooms aside while you prepare the filling.
Change oven settings to 375ºF regular oven. (Not broiler, not fan).
Make the Filling
Add onion, sun dried tomatoes, spinach, garlic, and any washed mushroom stems you may have, to a food processor. Pulse until minced to almost a paste, and very well combined. Add red pepper flakes, and a few pinches fine salt. Crumble in about half the feta cheese and stir to combine (or pulse a few more times). Alternatively, you can finely mince the vegetables instead of using a food processor.
Assemble the Mushrooms
Return to the mushrooms. Feel free to add a layer of parchment paper under the mushrooms at this stage. Drain off any additional water that has accumulated in the mushroom caps or on the tray. (This water is delicious - save it! See notes.) Arrange the filling around the edges of the 4 mushrooms, making a donut shape on the perimeter and a large well in the middle for the egg.
Crack an egg into each well. Medium or smaller eggs are ideal here, and even still, some egg white might run out onto the sheet pan - it is ok! That's what the parchment is for! Sprinkle with a little salt & pepper, and the rest of the crumbled feta.
Bake mushrooms on 375ºF for about 15-20 minutes or until the egg white is fully cooked. I find it challenging to get a cooked egg white and a runny yolk, so if you really prefer a runny yolk, I would bake the stuffed mushrooms without the egg and then add a fried or poached egg on top.
Top with minced chives or other chopped herbs (optional), and whatever sides you prefer.
Notes
You may need to adjust the amount of veggies depending on the size of your portobellos.
Cost-saving tip: Buy portobello mushrooms on sale or make a trip to the farmer's market, where I find them to be more affordable.
Use small or medium-sized eggs. These fit better in the mushroom caps and spill out less on the baking sheet.
Use parchment paper on the baking sheet to save some clean-up time in case your eggs overflow. BUT add it to the pan after broiling the mushrooms. (It is not safe to broil parchment paper.)
Don't throw out the mushroom juice! Instead save it to add to a vegetable broth or soup for an intense mushroom flavor.
Serving idea: It goes great with roasted potatoes or a piece of toast with nut butter and blueberries.