Place a large sauce pot over medium heat. Add the butter, oil, chopped and cleaned leeks, cumin and the Cuban seasoning. Saute 3-5 minutes until the leeks soften.
Heat the stock in another sauce pan or in the microwave. Keep warm.
Add the rice to the leek mixture, followed by the white wine. Stir and simmer until the wine absorbs.
Add 1 cup of stock at a time, stirring and allow it to absorb into the rice before adding more. This should take 15-20 minutes until all the stock is incorporated and the rice is "al dente".
When the rice is tender and creamy, stir in the Parmesan cheese. Salt and pepper to taste.