There are different routes you can take to figure out the mass or volume of cheese if the moon were made entirely of it. Here is one method:

The dimensions of a 1kg block of cheddar cheese from the supermarket is around 10cm*10cm*10cm or 0.001m³

I’ll estimate the radius of the moon to be 2000km and thus the volume to be:

(4/3)*pi*2,000,000³= 3.3510322e+19m³

So the mass of cheese would be (3.3510322e+19)/(0.001)=3.3510322e+22kg

I’ll say that 0.1kg of cheese are used for each pizza. So the number of pizzas is:

(3.3510322e+22)/(0.1)=3.3510322e+23 pizzas, which I’ll round to 3e+23 or 300,000,000,000,000,000,000,000.

The new questions is how long would it take to eat all of this?

If I take the world population to be 8 billion, each person would need to eat:

(3e+23)/(8e+9)= 3.75e+13 pizzas

You would need to eat over 1 billion pizzas every day to meet this quota.