12 ounces kielbasa, andouille, or other spicy sausage, sliced
8 thick slices crusty white bread
½ cup chopped scallions
Preheat the oven to 400°F. Place the potatoes in a saucepan and cover with water. Bring to a boil, reduce the heat, and simmer until they are firm but can be easily pierced with a fork, 11 to 12 minutes. Drain.
Meanwhile, combine the butter, oil, Old Bay, and salt in a small bowl.
Cut each ear of corn lengthwise into into three or four pieces, depending on long it is. Add the corn to a large bowl along with the potatoes, shrimp, and sausage. Add 4 tablespoons of the butter-spice mixture and toss to coat. Transfer to a rimmed baking sheet and roast until the shrimp is cooked through, the corn is slightly tender, and the sausage sizzles at its edges, 15 to 17 minutes.
Meanwhile, brush 8 slices of bread with the remaining butter-spice mixture. Arrange on a baking sheet, and bake until toasted and golden, 10 to 11 minutes.
Remove both trays from the oven and garnish the “boil” tray with the scallions. Serve with the buttery spiced toasts.