Cook potatoes in boiling water in saucepan for 10 min.
In a large saucepan over medium-high heat, pour in ¼ cup olive oil. Line a baking sheet with paper towels.
Put ½ cup of the flour in a small bowl and season with salt and pepper. Add the sliced shallots and toss to coat evenly. Working in batches, fry the shallots until golden brown and lightly crisped, 5–6 minutes. Set aside.
Drain potatoes; place in 2 ½ qt. casserole dish coated with 1 Tbsp. olive oil.
Add 1 Tbsp. olive oil to a large nonstick skillet on medium heat. Add leeks and cook 5 min. or until tender. Stir in 1 ¼ cups of broth.
Whisk flour and remaining ¾ cup broth in small bowl until blended. Gradually stir into ingredients in skillet; cook 2-3 minutes or until thickened, stirring constantly.
Add cream cheese, milk, and ½ cup shredded cheese; cook and stir 4 min. or until melted.
Heat oven to 400˚F. Cover with leek mixture; top with remaining shredded cheese and fried shallot rings.
Bake 20 min. or until potatoes are tender and sauce is heated through. Serve warm and enjoy!