Large handful fresh basil, leaves only, plus more for garnish
Salt, to taste
For the croquettes:
2 tablespoons extra virgin olive oil
1 white onion, finely diced
4 garlic cloves, minced
16–18 cremini mushrooms, cleaned and finely chopped
Few pinches of of salt, plus more to taste
3 tablespoons butter
3 tablespoons all-purpose flour
1cup milk
Provolone, grated, as needed
Parmigiano reggiano, grated, as needed
Italian breadcrumbs, as needed
2 large eggs, whisked
1/2cup all purpose flour
2cups panko
Neutral oil, for frying
Instructions
Add tomatoes, garlic, and Calabrian chilis to a medium pot and season with salt. Bring to a simmer, remove from heat, and add fresh basil. Use an immersion blender to mix everything together until the sauce is smooth. Taste and adjust as needed. Set aside to fully cool and then refrigerate.
Coat a large pot over medium-low heat with extra virgin olive oil. Add onion, garlic, mushrooms, and salt, and sweat until onions and garlic appear cooked and mushrooms are tender. Transfer everything to a bowl and set aside.
Add butter and flour to the pot. Cook and stir until aromatic and well combined, while avoiding browning. Add milk, increase the heat, and stir until thickened. Fold the onion, garlic, and mushroom mixture back into the pot. Allow to cool, transfer to a covered bowl or container, and chill for 3-4 hours.
Remove mixture from fridge and assess the consistency and texture. Add grated provolone, parmigiano reggiano, and Italian breadcrumbs in small amounts, combining as you work until the mixture feels firm enough to shape. Using a spoon, scoop small amounts (slightly larger than a tablespoon) of the mixture and roll them into balls. Transfer to a tray and chill or freeze until ready to cook.
Set up a dredging station with three bowls—filled with flour, eggs, and panko, respectively. In a large pot, heat neutral oil to 360 F, or until shimmering. Coat each ball with flour, egg, and panko (in that order), and transfer to pot until golden brown. Work in batches to avoid overcrowding and dropping oil temperature. When the croquettes appear golden brown (about 3-4 minutes, or slightly longer if cooking from frozen), transfer to a rack over a tray to catch any excess oil, and sprinkle with salt.
Reheat marinara sauce and add to a dipping bowl with fresh basil for garnish (but also to tear apart and eat). Pile croquettes onto a serving plate or platter and enjoy.