Heat your oven to 400ºF.

Add the butter to a small baking pan and place it in the oven for a minute or two, until melted. Stir in 1/2 teaspoon vanilla extract.

Cut each pear into 6 sections; remove and discard the stem and seeds. Place the pears, cut side down, into the melted butter. Roast 10-15 minutes, or until the pears are soft and begin to brown at the edges. Use a slotted spatula to remove the pears from the pan, reserving the vanilla butter.

Spread the pecans on a baking sheet and roast for 6-8 minutes, or until toasted. Transfer to a small bowl. Add the vanilla butter and stir to coat. Stir in the brown sugar, cinnamon, salt, and cayenne pepper, coating the nuts evenly. Let cool.

Meanwhile, prepare the vanilla vinaigrette. In a small bowl, whisk together the olive oil, vinegar, 1 teaspoon vanilla extract, and honey. Season to taste with salt and pepper.

To serve, toss the salad greens with 1/4 cup of vinaigrette. Divide among four plates. Top with pear slices, spiced nuts, and cheese. Top with prosciutto, if using. Serve with remaining vinaigrette.