Preheat oven to 375 degrees. Line a baking sheet with aluminum foil.
Brush both slides of each slice of bread lightly with olive oil. Bake for 10 minutes, flipping once. Cool.
Quarter the apples and then remove the core. Slice into 1/8-1/4 inch slices. Toss with a squeeze of fresh lemon juice to prevent browning.
If using prosciutto, start with a really thin layer of mascarpone cheese on the baguette. Top with prosciutto. Top with more mascarpone, about ½-1 tablespoon. Spread with a ½ teaspoon or so of fig jam. Top with an apple slice.
Serve.