Preheat the oven to 400°F. Line a large baking sheet with aluminum foil or parchment paper; set aside.

Cut and peel the white sweet potatoes into 1-inch chunks, and the tri-colored small potatoes into halves and quarters depending on size.

Place all potatoes in a large bowl and add the olive oil, melted butter, minced fresh rosemary, garlic powder, salt, and pepper. Toss potatoes until fully coated. Dump the potatoes onto the lined baking sheet, spreading them out into a single even layer.

Roast for 45-50 minutes, flipping halfway through, until light golden brown and tender.

Garnish with additional minced rosemary and serve.