Chili stout.

Dried ancho chiles are good in a stout. They have heat, and a dark plum and raisin flavor.
Not sure if I would add them to the bottle, I let mine soak in a spirit for 24 hrs ahead of time, then pitch the whole thing into secondary.

 

I use habanyero, 1 pepper the last 10 minutes of the boil. Then fish out the pepper. Peppering the bottles may make an overly hot brew.

 

Another vote for a tincture made with vodka. Soak your pepper of choice for as long as you want. I like habanero as well. You can add the tincture to taste with the amount you are bottling.

I have never had good results with extra fruit/vegetable matter in bottles. Almost always results in foaming due to the increased nucleation points.

 

I have an award winning jalapeno stout where I make the beer as normal without any peppers, then on the same day the beer is kegged or bottled, chop about 8 jalapenos per 5 gallons, seeds and all, add about 3 cups of the finished beer from the fermenter, bring to a boil for about 10 minutes, cool, then add the flavored beer back into the main beer. Makes a fantastic flavor and heat that you just can't get from any other process.

8 jalapenos makes a medium heat that fades after 2-3 minutes per gulp. I don't have experience with other peppers but if habanero, I would use only 1/2 to 1 and without seeds. Other types, not sure. Some experimentation and common sense required.

 

Nucleation points, love it!!, yes I get the foam when residual matter gets in the beer, but , I find the excessive foaming stops after 6 months.

 

If you want a chili flavor beyond the het from peppers I think you'd need to use some chili spices to mimic that flavor. I'd check some chili recipes to see what to use. Cumin comes to mind as a chili ingredient, but I'm unsure of that as a major flavor source. Smell some to help you decide. How much to use of whatever you choose? Until you find someone who has done before, I think you'll need to experiment.

 

These are my favorite.

https://www.thespicehouse.com/meco-brown-chipotle-chile-peppers

I first used them years ago in a beer I called "Zimmerman Telegram Conspiracy". And, damn, now I'm in the mood for some! Time to bring that one back around for the summer BBQ season.

 

~2 Roast Hatch Chiles (frozen) bagged and dry hopped in keg/secondary

 

I do a habanero IPA. Pepper is chopped (no seeds) and soaked in vodka for a couple of days. Then added during last 3 days of fermentation, and removed at bottling. I find that one pepper for 3 days in a 5 gal batch will give a slight amount of heat and decent habanero flavor. This is the way to go if you're a mild salsa or chili kind of person. Two peppers is the sweet spot for me, just enough heat but not overbearing (think medium salsa). Haven't gone with any more than that. Also, I use the light green peppers which are not fully ripened and on the mild side as compared to the red ones.

 

I've made a delicious stout with chipotles and raspberries.

Dried chipotles at the end of the boil and leave them in for a few days into fermentation until fishing them out.
Then I buy a bag of frozen raspberries. Heat them on a stove till a simmer mashing a few to get the liquid. Then add to the beer in a secondary.

It has very little spiciness but great flavor from the chipotles with a bit of tanginess from the raspberries. It's gone over well.

I want to explore more with ancho chilis and hatch peppers though.