1. Preheat oven to 400°F. Prick sweet potatoes all over. Place on parchment paper–lined baking sheet; bake for 45 to 60 minutes or until tender. Let cool slightly, then peel.
2. Mash together sweet potatoes, cubed butter, milk, salt and pepper. Stir in egg yolk. Fold in salami, pepperoni, provolone and green onions; set aside.
3. Reduce oven temperature to 375°F. Working with one phyllo sheet at a time and keeping remaining sheets covered with damp towel, cut into 3-inch squares. Brush each square lightly with olive oil.
4. Place 3 squares into mini muffin cup. Repeat to fill 24 mini muffin cups; divide sweet potato mixture among cups. Bake for 10 to 15 minutes or until golden brown.

Tip: Alternatively, microwave sweet potatoes for 8 to 10 minutes or until tender.