Adjusting a Porter recipe

So, I brewed a robust porter that turned out really well. The only problem is that it is a little bit boring. It has a nice, clean flavor in which the malt is featured prominently. But I think it would do well with maybe some chocolate (cacao nibs?) and vanilla beans in secondary.

Here is my original recipe (partial mash):

5 .25 gallon batch

3 lbs. Maris Otter
1 lb. Amber malt
10 oz. Chocolate malt

6 lbs. Maris Otter LME (flame-out addition)

1 oz. UK Phoenix - 60 min. - 30 IBU
1 oz. UK Kent Goldings - 12 min. - 6 IBU
1 oz. UK Kent Goldings - 2 min. - 1 IBU

1 oz. UK Kent Goldings - dry-hop - 7 days

I originally planned on using some Fuggles in the 12 min. addition, but the package had gone bad at some point and smelled terrible. So, I went with the UK Kent Goldings that I had on hand. Seeing as how I was planning on using some of the Goldings in this brew anyway, I figured it was fine.

As I've been drinking it recently, I've enjoyed it but would like to enhance it a bit for the next time around. I'm thinking of upping the Chocolate malt slightly, subbing in some Biscuit malt in place of the Amber malt. Adding some Crystal 60L and flaked barley. I'm also planning on getting rid of the dry-hopping step, as it didn't really seem to show up in the final product.

So, here's where I'm at with my revision:

5 .25 gallon batch

3 lbs. Maris Otter
12 oz. Chocolate malt
12 oz. Crystal 60L
8 oz. Flaked Barley
8 oz. Biscuit malt

6 lbs. Maris Otter LME (flame-out addition)

1 oz. UK Phoenix - 60 min. - 31 IBU
1 oz. UK Kent Goldings - 8 min. - 5 IBU
1 oz. UK Kent Goldings - 2 min. - 1 IBU

And like I mentioned earlier, I'm thinking about adding something chocolate and vanilla beans. I remembered the BrewingTV episode when Chip used baker's chocolate, and I know some people use coco powder and cacao nibs as well. Through some searching/reading I've settled on about 8 oz. of cacao nibs for a couple weeks in secondary. I am thinking of using 2 or 3 vanilla beans, but I'm not sure how long to have them in secondary. I'm not sure if I should add them at the same time as the cacao nibs or if they need a longer/shorter time.

Any advice or thoughts would be appreciated. I'm not sure when I might brew this. Probably not until after I've finished drinking the first batch. In adjusting this recipe, my goal is to end up with more substantial flavor profile, even if I leave out the cacao nibs and vanilla beans.

I would steep .5lb of C60 and .5lb of C120.

I had thought of adding some C120, but figured I should maybe hold back a bit on the darker malts and maybe adjust again after another batch. I'm obviously not worried about the color, because it is a porter after all. I guess I want to be sure all of the flavors are necessary, rather than throw in a bunch of dark malts and not being sure what is what.

Well the C120 will give you raisin/ fig notes. The roasted malts will give you toast, chocolate, coffee, etc.

Would the combination of C60 and C120 leave more unfermentable sugars? That might not be a bad thing considering the cacao nibs and vanilla. Both of those would be brought out more with a little residual sweetness.

But would it be too much? I don't want to end up with a beer that is overly sweet.

All Crystal malts will leave unfermentable sugars. For a robust porter that you're going to add nibs and vanilla, no. It shouldn't be too sweet. Like you say, it will increase the perception of milk chocolate and vanilla.

I would be more concerned with attenuation and using extract leaving the beer too sweet. What % attenuation do you usually get?

And honestly, if it's too sweet, you can always add some bourbon soaked oak cubes to cut that down. That would play really nicely with the cacao and vanilla. But I doubt it'll be cloyingly sweet or undrinkably so.

I haven't really calculated my attenuation percentage consistently, and I tend to switch up the yeast I use so that has made it hard to bank on a predictable attenuation. But with this porter (the first recipe listed in the op), I went from 1.060 OG down to 1.016 FG.

I'd probably use the same yeast, seeing as how I washed the yeast and saved it. I just recently started this technique, so I may start using the same yeast more consistently. I'm using it in a rye standard bitter right now, and will wash it again after that batch. So, I'll have plenty of viable yeast and will do a decent sized starter, as well.

Also, I guess if I add just a half pound of C120, like you suggest, it wouldn't change the sweetness all that much. And considering how dry my original batch tastes, a total of a pound of crystal malts probably isn't going to be too much.

Sounds like a plan, dude! Keep us posted w/ the final recipe and results.