When people say a bigger beer then they normally mean more ABV.
If you mean maltier then you need a wort that isn't as fermentable which means mashing at a higher temp and maybe adding adjuncts to give more body like cara malts and maltodextrin. You use a standard base malt.
Here's extract recipe. Can't vouch for it though.
Newcastle Clone Recipe
Simple little recipe that tastes similar to Newcastle Brown Ale. Personally, I like to add an ounce or two of biscuit malt to add a little more complexity.
Ingredients
# Grains: 2 oz 60L Crystal Malt
# 2 oz Chocolate Malt
# 1 oz Black Malt
# Extracts: 6 lbs Light DME
# Hops: 6.5 HBUs Target Hops (Bittering) I usually use 1 oz of Fuggles Hops
# 1/2 oz East Kent Goldings (Flavor)
# Yeast: British Ale Yeast
Instructions:
Put the specialty grains into the muslin bag and steep in 150 degree water for 20 minutes. Pull the bag out, allowing it to drain freely into the brew kettle. There is no need to "squeeze" the bag. Squeezing the bag will only release tannins that will harm your beer.
Add 170 degree water to the brew kettle to bring the total volume to 2.5 gallons. As you add this water, run it over your bag of grains to sparge ("rinse") the rest of the grain water out of the bag.
Bring kettle to a boil, then remove it from the burner. Stir in the Dry Malt Extract (DME), and put Target (Bittering) hops in a muslin bag (tied closed) and add into the kettle.
Return to heat and boil for 45 minutes. Add the 1/2 oz East Kent Goldings to the muslin bag and boil for 15 minutes.
Cool to room temperature, add water to bring total volume to 5 gallons. Stir vigorously to incorporate air into the wort. Pitch (add) your yeast.
Here's an AG, again can't vouch.
All Grain Recipe - Newcastle Brown Ale ::: 1.050/1.014 (5.5 Gal)
Grain Bill (75% Efficiency assumed)
9 lbs. - Maris Otter - 2 Row malt
2 oz. - Chocolate malt
2 oz. - Crystal malt (60L)
1.5 oz. - Black Patent malt
Hop Schedule (25 IBU)
1/2 oz. - Target - 60 min.
1/2 oz. - East Kent Goldings - 15 min.
Yeast
White Labs British Ale Yeast (WLP005) - 1800 ml starter
Mash/Sparge/Boil
Mash at 154° for 60 min.
Sparge as usual
Boil for 60 minutes
Cool and ferment at 68° to 71°
Recipe adapted and changed slightly from the one found in Clone Brews