Cut your washed and peeled russet potatoes into uniform fries. Soak them in cold water for 30 minutes to release excess surface starch, then pat them completely dry with paper towels. Toss the dried potatoes in a large mixing bowl with vegetable oil, garlic powder, sea salt, and a light dusting of cornstarch until evenly coated.

Preheat your oven to 425°F (218°C). Spread the seasoned potatoes across a large baking sheet in a single layer, ensuring they do not overlap so they steam-fry correctly. Bake for 20 to 25 minutes, flipping halfway through, until the edges turn deeply golden brown and perfectly crisp.

While the fries bake, place chicken breasts, homemade taco seasoning, and chicken broth into a saucepan over medium heat. Simmer covered for 15 minutes until the internal temperature hits 165°F (74°C). Remove the chicken from the liquid and use two forks to pull it into fine, seasoned shredded chicken shreds, then toss it back into the remaining pan juices.

Warm the heavy cream in a saucepan over low heat until it just begins to simmer. Slowly whisk in the freshly shredded Cheddar and Monterey Jack cheeses one handful at a time, stirring constantly until fully emulsified into a smooth, glossy sauce.

Transfer your hot, crispy fries into a oven-safe cast-iron skillet or keep them on the baking sheet. Layer the seasoned shredded chicken generously over the top, then pour the hot melted cheese sauce across the entire surface. Return the skillet to the oven under the broiler for 2 to 3 minutes until bubbling.

Remove the sizzling skillet safely from the oven. Garnish immediately with diced Roma tomatoes, sliced pickled jalapeños, fresh cilantro, and a heavy drizzle of cool sour cream before serving warm.