01 -
Move your oven rack to the top and warm it to 425°F. Grab a pot and melt the butter with 3 tablespoons oil over low-medium heat. Toss in your chopped garlic, oregano, and pepper flakes. Cook them until the garlic gets soft but stays light colored, around 2 minutes. Stir in half your fresh herbs and some salt, then take it off the heat.
02 -
Cut your bread down the middle and across, then lay it with the cut sides up. Push down gently with a baking tray to flatten it a bit, making it about 2/3 as tall. Put it on the tray and brush half your butter-garlic mix all over the cut parts.
03 -
Pour those smashed tomatoes into what's left of your garlic-butter mix. Let it bubble on medium heat, then turn it down and cook till it gets thicker, about 15 minutes. Add salt till it tastes right.
04 -
While your sauce cooks down, spread 1/4 of your shredded mozzarella on the bread and stick it in the oven till it barely starts melting, about 8 minutes.
05 -
Spread your sauce over everything, add the rest of your mozzarella, and bake till the cheese gets all melty and starts turning golden, about 10 minutes. Scatter the Parmigiano-Reggiano on top with the leftover herbs and that last tablespoon of oil. Let it sit for a bit before you dig in.