Using a serrated knife, thinly cut the baguette on a very sharp diagonal into 3-inch-long slices. Brush the baguette slices with olive oil and season lightly with salt and pepper. Arrange the baguette slices on a baking sheet and bake for 4 to 6 minutes, or until light golden brown and crisp.
While the crostini are hot, rub the garlic clove over each. Set the crostini aside to cool completely. Maintain the oven temperature.
In a small saucepan, combine the champagne and cherries and bring to a boil over high heat. Transfer the mixture to a bowl and set aside to cool completely, tossing occasionally. Tear the cherries in half.
Sprinkle the goat cheese over the crostini and top with the cherries. Tear the prosciutto slices into about 2-inch pieces and arrange them over the crostini. Bake for about 2 minutes, or until just warm.
Garnish with arugula and a light drizzle of olive oil. Sprinkle with pepper and serve immediately