Preheat the oven to 400 degrees F/204 C. Brush 6 cups of a 12-cup muffin tin generously with melted butter*.
Thinly slice the potatoes using a mandoline with a handguard (aka handrail), or using a sharp knife to approximately 1/16 - ⅛ thickness.
Transfer the potato slices into a large bowl*. Add 2 tablespoons of olive oil, minced rosemary, garlic powder, kosher salt, and black pepper. Toss to combine.
On a clean work surface, lay out a slice of bacon, then place the potato slices overlapping each one until you have used approximately 20 slices.
Sprinkle 1 to 2 tablespoons of Parmesan cheese over the potatoes.
Gently roll up the combined bacon and potato slices until it has formed a rose.
Place your potato rosette in a muffin cup and add 10 more potato slices around the bacon-wrapped rose. If needed, you can adjust the potato slices to “fluff” out the edges of your rosette more.
Repeat with the remaining bacon, potato slices, and cheese. You will have 6 potato roses when you’re finished.
Place your muffin tin in the oven and bake, uncovered, for 20 minutes. Then place your foil on top of the potato roses and bake for an additional 30 minutes, or until tender and cooked through. A sharp paring knife, when inserted into the middle of the potato rose, will pierce the potato center easily.
Let your potato roses rest for 10 minutes, then gently run a paring knife on the outer edge of each rose to remove them from the muffin tin. Place onto a serving platter.