Heat the oven to 425°F.
In a food processor or a large bowl, combine the butter, Parmigiano, oil, garlic, lemon zest, 1/4 tsp. salt, and 1/8 tsp. pepper. Pulse a few times to blend but don’t overprocess or the butter might separate. If mixing by hand, mash together with a fork or a wooden spoon.
Slice the bread 1 inch thick, cutting almost but not all the way through the bottom crust, so it’s easy to pull apart. Spread a light, even coating of the butter mixture on both sides of each slice of bread. (You may not need all the butter; refrigerate any leftover for up to a week or freeze for up to three months.) Wrap the bread in foil and put the loaf on a baking sheet to catch any butter that runs out. Heat in the oven for about 15 minutes, then open the top of the foil to slightly crisp the top of the loaf, about 5 more minutes. Serve while hot.
nutrition information (per serving):
based on six servings;
Photo: Scott Phillips