#but the fact that I've improved on one of their old bookmarked recipes is making me feel quite satisfied

[falderaletcetera]

brownie update: swirling crunchy peanut butter through the batter is great. swirling it through only when it's already in the pan, so you get attractive golden marbling and a distinct top layer of crisp crunchy peanut butter brownie goodness, is even better.

(original recipe)

general notes:

— if adding peanut butter, you might need to heat it up a little in the microwave to thin it out enough first. the weight recommended for nuts in the recipe works fine.

— you can in fact substitute both eggs for one banana - I blended it rather than mashing it because I don't like lumps - and yes the result does taste like banana.

— you can also substitute butter for oil: use around 7.5 tablespoons. you might need to add a few tablespoons of water to make the mixture behave; butter does have water in it too. (I started doing this because I like shelf-stable ingredients and kept doing it because lactose intolerance. ideal.)

— personally I deliberately overbake these a touch because I've had too many "oh that's a volcano in the middle" Underbaking Events, and even aside from them, the middle pieces can be very soft.

— you can use a 9" round cake tin if you don't have an 8x8 square tin - it's almost exactly the same area and I've tested it - it's just a bit of a faff to cut up neatly. any tin smaller than the one recommended will lead to Underbaking Events no matter how much extra time you add.

— in british terms the oven temp is pretty much 160 C. don't use fan.

— I have never bothered with vanilla (I don't bake often enough and time is fake so it's a "blink and it's expired" situation) and it's fine

— the "pop it in the freezer for a bit so it cuts neatly" advice in the recipe is magic, actually

— these freeze fine! just keep the pieces separated if you want to defrost them individually.