Horseradish & Leeks Pasta Bake

2-3 cups grated Parmesan cheese  

1 medium horseradish root

3 large leeks, chopped 

tomato sauce (I always go for putanesca but there are plenty around)

300g pasta

Cook pasta to within half the suggested by the packaging cooking instructions time. Drain and drizzle with olive oil and hold in bowl covered with plastic wrap. Peel and grate horseradish root on box grater or in food processor. 
Scrub with a stiff brush and peel off the dark skin before using the root. When grating horseradish, it is easiest to use a food processor. Cut the peeled root into cubes and pulse to the desired consistency. The fumes will be quite strong and can actually burn your nose and eyes. Be sure to open a window, remove the lid at arm's length, and turn your head away. If you are brave enough to grate it yourself make sure you are extra careful.

This needs to be done immediately before using. Horseradish will discolor if grated too far in advance. Mix finely grated horseradish with chopped leeks and 2 cups of the grated cheese adding salt and pepper.
In large casserole, layer tomato sauce, pasta and horseradish mixture. Finish by topping with tomato sauce and grated cheese. Mixture should be somewhat soupy. Cover and bake for 20-30 minutes in a 350 degree oven. Uncover and cook 10 more minutes. Serve with extra grated cheese.