Mussels are a very affordable seafood option and they cook really quickly. Once you add them to the sauce, they’re ready in less than 10 minutes. Talk about fast food!
Preheat the oven to 350°. Arrange the baguette pieces, cut-side down, on the oven rack and toast until crisp, about 7 minutes.
In a small pan, melt the butter and EVOO. Add the garlic, swirl for 1 minute, and remove from the heat. Brush the baguette halves liberally with the garlic butter and sprinkle with the parsley. Slice into 3-inch pieces and set aside while you prepare the mussels.
In a large pot or bowl, soak the mussels for 15 minutes in very cold water; drain.
Heat a large pot or Dutch oven over medium to medium-high. Add the olive oil, two turns of the pan, and 2 tbsp. butter. When the butter melts, add the shallots, garlic, and lemon zest. Season with salt and crushed red pepper. Stir until the shallots soften, 3 to 4 minutes. Add the wine; bring to a boil. Add the mussels, cover the pot, and cook, stirring once halfway through cooking, until the mussels open, 6 to 8 minutes. Discard any mussels that don’t open. Stir in the remaining 4 tbsp. butter, the parsley, and lemon juice.
Arrange half of the bread around the edge of the pot. Serve the mussels from the pot, setting out bowls for guests. Place an empty bowl on the table for discarding the shells. Serve with the remaining bread.