2 lbs leeks, root and dark green cut away. Use only white and light green parts
1 TBS olive oil
6 TBS butter, melted
salt and pepper
Preheat oven to 350 degrees. Cut leeks lengthwise and rinse well. Cut into 1/4 inch slices.
Put the leeks on a large rimmed baking sheet and drizzle with olive oil and melted butter.  Spread out on the baking sheet.
Bake for 1 1/4 hrs, stirring every 15 minutes until the leeks are carmalized and brown.

You can stop baking them when they are soft and slightly brown, about 45 minutes if they are better to your liking.
These can be refrigerated until ready to use up to 1 week.