Dice the potatoes into 1-inch cubes.

Boil the diced potatoes in a large pot for 15 minutes, or until tender but not mushy.

Drain the potatoes, rinse with cold water, and drain again.

Place the drained potatoes in a large mixing bowl.

Thinly slice the leeks.

Mince the garlic cloves.

Dice the tomatoes.

Melt the butter in a large skillet over medium-high heat.

Add the garlic and leeks to the skillet and saute until the leeks become tender.

Add the diced tomato, salt, pepper, paprika, and parsley to the skillet.

Stir the ingredients well.

Reduce heat to low.

Stir in the evaporated milk, cream cheese, and sour cream until well-blended.

Stir in the shredded cheddar and Swiss cheeses; combine well.

Pour the cheese sauce over the drained potatoes and gently toss to coat.

Pour the potato mixture into a lightly sprayed 13x9-inch baking pan.

Bake uncovered at 350°F (175°C) for 30-35 minutes, or until the top begins to slightly brown.