Preheat the oven to 400°F (200°C) and line a baking sheet with parchment paper.
In a large bowl, toss the thinly sliced potatoes with olive oil, minced garlic, smoked paprika, Italian seasoning, salt, and black pepper until well coated.
Arrange the seasoned potato slices in a single layer on the prepared baking sheet.
Bake for 25 to 30 minutes, flipping the slices halfway through, until the potatoes are crispy and golden brown.
Remove the baking sheet from the oven and evenly sprinkle mozzarella and Parmesan cheeses over the potato slices.
Top with sliced jalapeños if using, then return the baking sheet to the oven.
Bake for an additional 5 to 7 minutes, or until the cheese is melted and bubbly.
Let the nachos cool slightly, garnish with chopped fresh parsley, and serve with sour cream or Greek yogurt.