I would start with Denny's Conn's famous recipe:
Vanilla Imperial Porter ::: 1.079/1.017 (6 Gal)
Grain Bill (70% Efficiency assumed)
13 lb.- 2-Row Pale Malt
2.5 lb. - Munich Malt (15 L)
1.5 lb. - Brown Malt
1 lb. - Crystal Malt (120L)
1/2 lb. - Crystal Malt (40L)
1.25 lb. - Chocolate Malt (edited - Thanks Denny)
Extras :
Real, Whole Vanilla Beans (Extract just won't do)
Oak Chips or Cubes
Hop Schedule (37 IBU)
1 oz - Magnum Hops (60 min)
1/2 oz - E.K. Goldings (10 min)
White Labs California Ale Yeast (WLP001) - 1800 ml starter
Mash/Sparge/Boil
Mash at 153° for 60 min.
Sparge as usual
Cool and ferment at about 68° Add Vanilla Beans after primary - rack 7 to 14 days
This is even better with denny's favorite 50 yeast - wyeast 1450
I took the Bourbon out of this recipe to simplify the recipe for you.