Preheat oven to 350F.
Cook bacon in large frying pan.
While bacon is cooking, slice leek.
Add broccoli to a food processor and pulse until it's completely broken up. You may need to do this in batches depending on the size of your food processor.
Shred cheese.
When bacon is finished, place aside on a plate lined with paper towels to soak up the grease. Add leeks to the hot pan with bacon grease and cook until softened.
In the meantime, add the eggs, cream, dairy-free milk, salt, and pepper to a big bowel. Use a hand mixer to blend for a minute.
Prepare a plate lined with paper towels. Scoop leeks out of pan and place on plate. Blot with paper towels to absorb excess grease.
Once bacon is cooled, chop into bits.
In a round casserole dish (at least 9" diameter), pour a drizzle of olive oil. Use wax paper to evenly cook the bottom and sides of the dish.
Layer the dry ingredients starting with cheese, then 1/3 of the broccoli, 1/3 of the bacon, 1/3 of the leeks, and repeat until all ingredients are added. Pour egg mixture over the entire dish evenly.
Place on baking sheet and insert into oven on the middle rack.
Set timer for 50 minutes. It should be done between 50-60 minutes.