first of all put it in hot boiling water to make it unstuck then put a spatula under neath if you cant get it off go to next step with spatulas under put soap and butter Tadd Dada its out if you need...
You can but the mixture will be less thickly spread in the 9 x 13 pan. You may want to increase the amount of batter that you use (assuming you're making a cake or something that spreads to fill the...