Heat the oven to 400°F (200°C) and line a baking sheet with aluminum foil.

Trim and halve or quarter the potatoes so pieces are roughly the same size for even roasting.

In a large bowl, combine olive oil, melted butter, powdered buttermilk, minced garlic, dried thyme, oregano, parsley, and onion powder. Toss the potato pieces in the mixture until well coated.

Spread the seasoned potatoes in a single layer on the prepared baking sheet.

Roast for about 25 minutes. Remove the pan, give the potatoes a good shake and flip them so they brown evenly.

Arrange the bacon slices over the potatoes and return the sheet to the oven. Roast another 20 to 25 minutes, or until the potatoes are crisp and the bacon is cooked through.

While the potatoes finish cooking, place the shredded mozzarella and cheddar together in a small bowl.

Take the baking sheet from the oven and transfer the bacon to a cutting board. Chop the bacon into small pieces.

Scatter the shredded cheeses and chopped bacon evenly over the hot potatoes, then return to the oven just until the cheese melts, about 5 minutes.

Move the potatoes to a serving dish, drizzle with ranch dressing, and serve immediately. Offer extra ranch on the side if desired.