Remove Mini Fillo Shells from the freezer and allow to thaw.

Arrange grapes in a single layer on a parchment-lined baking sheet

Drizzle olive oil over grapes

Roast grapes at 400 F for 15 minutes or until the grapes begin to burst. Do not over-roast as the grapes will begin to char

While grapes are roasting, combine mascarpone cheese, honey, and vanilla bean seeds (do not add the pod)

Place a thin layer of chopped walnuts on the bottom of each mini fillo shell

Fill each tart with the mascarpone-honey mixture using a pastry bag (you can also place in a Ziploc bag and cut off a small portion of the tip)

Allow grapes to cool before placing on top of each tart

Garnish with rosemary

Serve immediately