Thinly slice a baguette; arrange in a single layer on a baking sheet. Brush with olive oil and sprinkle with salt. Bake at 425 degrees F until lightly golden, about 7 minutes. Let cool slightly.
Toss 1 thinly sliced shallot, 3 tablespoons olive oil, 1 teaspoon chopped rosemary and a pinch of salt; set aside 10 minutes. Spread softened butter on the toast rounds. Top with sliced bresaola (cured beef) and the marinated shallot. Drizzle with the marinade.