"This amazing Calabrian pepper spread is as delicious as it is unknown. I love it on sliced fresh bread, but you can toss it with pasta, add it to a sandwich, fill an omelet, top a pizza, or serve as salsa with grilled fish, or in deviled eggs."
Place mushrooms, onion, and eggplant into bowl of a food processor. Pulse on and off until very finely chopped but not liquefied, 8 to 10 pulses.
Drizzle 2 tablespoons olive oil into a skillet. Transfer mushroom mixture to skillet over medium-high heat. Add a large pinch of salt. Cook until mixture is soft, stirring, about 10 minutes.
Cut off tops of cherry peppers; discard stems but save the ring of pepper around it. (Do wear protective gloves for this.) Cut the peppers in half and remove the seed pods. Shake out the rest of the seeds. Prep the bell peppers and habanero peppers the same way. Place all peppers in bowl of food processor. Pulse on and off until peppers are very finely chopped, but not liquefied. Transfer peppers to eggplant-onion-mushroom mixture in skillet. Add remaining olive oil. Cook and stir over medium-high heat, reducing heat as needed if mixture looks like it may brown. Add fennel seeds, oregano, and a pinch of salt. Cook until peppers are sweet and tender, 20 to 30 minutes, stirring occasionally. Remove from heat.
Stir in white wine vinegar and (optionally) another tablespoon of olive oil. Transfer mixture to a mixing bowl and cool to room temperature. Taste for seasonings, adding more salt, a splash of vinegar, and/or olive oil, if needed. Transfer to jars. Store in refrigerator.