3 gal. BIAB Vanilla Porter

I have a five gallon brew pot and would like to take my first shot at the brew in a bag method. With my capacity constraints I know I'll have brew a smaller batch to fit the grain needed for the BIAB. I'd like to brew a vanilla porter but can't find a recipe that's specific for a small batch BIAB. Does anyone have a good recipe? Or, willing to help me convert one based on my equipment/capacity?

I considered trying the Dry Dock URCA Vanilla Porter recipe from Norther Brewer but I'm not sure how to convert it, or if i have enough capacity. Any help would be greatly appreciated.

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This is my first time posting to HomeBrewTalk but I've been coming here for info since my first batch (only 3 batches in). There is a lot of great info here.

You can do any recipe, any size with biab. Since you're doing all grain you can just order the grains separately to do 3 gallons instead of the usual 5 that kits come in. I've had a lot of luck with the recipe database here to pick my recipes. I think brew masters warehouse has a feature where you can build a recipe and just order the grain you need, but I've never used it. As far as scaling the recipe down, download brewing software and that will do all the work for you. I personally use beersmith and know they have a free trial but the are others out there as well. Good luck, if you have any other questions just shout.