I am making a cake from scratch.  The recipe says it will make a 9"x13" cake.  I am using an 11"x15" pan.  Would doubling the recipe be enough to get a nice layer?  Thank you.

11x15 is only 29% bigger so double batter is WAY too much. One fourth more is ideal. Unless of course you are trying to make it taller than the original recipe. 

Continuing on what she ^^^ said to make a taller cake make a collar with parchment paper or foil by lining the sides oh the pan 2 or 3” higher  or just make cupcakes with the extra batter 

Oh & that will change how long it will bake   To ensure the center bakes put a flower nail in the center   If  you have never used one it helps conduct heat to the center of the pan   Place the nail with the  flat head part down & the nail sticking up  it will be easy to remove once the cake is turned out of the pan