A large one. Though to be more precise there would be 2 large cheques. There is one for the deposit and one for the closing costs.
I was the general contractor for our first house while working 70 - 90 hour weeks. It was exhausting but we got it done. And paid that mortgage off after 5 years. Since then we've traded up a number of times (all associated with career moves) and have always paid the difference in cash. Haven't had a mortgage payment for the last 4 houses.
We currently live in a very nice (but modest by many people's standards) 2400 square foot house on 1/2 acre. As I said, that's my plan and I'm sticking to it.