Belgian beer brewery

[Mary]

Hey! Which ingredients will I need to prepare a real monk beer? is it specific in preparation?

[seymour]

Hey! Which ingredients will I need to prepare a real monk beer?...

Water, malted cereal grains, simple sugar, hops, seldom a little coriander and orange peel, then yeast, in that order.

...is it specific in preparation?

Yes.

Do you have a specific beer in mind?

[Mary]

Yep! I wanna try Orval beer

[seymour]

Good call. One of the world's very best, no doubt. Brew Like A Monk a book by fellow St. Louisan Stan Hieronymous is very good, but the Orval brewer has since denied what he supposedly told Stan for that book. Whatever. I highly recommend it for in-depth background, techniques, temperatures, durations, pictures, etc, since you're obviously interested in this broad topic.

Meanwhile, these will certainly get you close:

Orval
Brasserie d'Orval in Florenville - Villers-d.-Orval, Belgium
OG: 1055
ABV: 6.8%
Grainbill: 72% 3 Pale Malts (Beauce, Gratinais, Unterfranken, Prisma?), 11.3% French CaraVienne and one other caramel malt, 16% Clear Sugar Syrup
Hops: Styrian Goldings & Hallertau (40 min), Styrian Goldings (late boil and dry hops)
Yeast: bottles contain primary strain and brett blend, primary strain is sold as White Labs WLP510

Orval Petit ("Monks' beer"/Belgian Enkel/Singel)
Brasserie dOrval in Florenville - Villers-d.-Orval, Belgium
OG: 1024
ABV: 3.4%
IBU: 21
Colour: 14°SRM/28°EBC, copper
Grainbill: 3 Pale Malts, 2 Caramel Malts, 16% Clear Invert Syrup (same Orval wort, added to a fermentor with more water)
Hops: Styrian Goldings & Hallertau (40 min), Styrian Goldings (late boil and dry hops)
Yeast: bottles contain primary strain and brett blend, primary strain is sold as White Labs WLP510

Goose Island Matilda (A Belgian-style ale, homage to Orval)
Goose Island in Chicago, Illinois,
ABV: 7.0%
IBU: 32
Colour: hazy golden
Grainbill: Pale, CaraMalt, Sugar
Bittering Hops: Styrian Goldings
Aroma hops: Saaz
Yeast: primary-classic Belgian ale strain, secondary-brett strain

Russian River Temptation (Belgian-style ale similar to Orval)
Russian River in Santa Rosa, California, USA
OG: 1062
ABV: 7.25%
Grainbill: Pilsener Malt, Unmalted Wheat
Hops: Styrian Goldings, Sterling
Yeast: 3 brett strains, aged in Chardonnay barrels
IBU: 27
Colour: hazy golden

[TheMumbler]

lancssteve did an Orval type of thing a while back that turned out well.
Le Caneton Vert dans les Couches

I think most trappist beers are deceptively simple in terms of ingredients, it is mainly about the yeast. Also don't be afraid of sugar as you will need some to get the low FG you are after to make them dangerously easy to drink for the abv.