Brushing breads and biscuits before they go into the oven with some sort of fat (or egg, or dairy) is a nice way to add colour and flavour, but we often seem to default to butter and olive oil when it comes to fat. I have nothing against those two fats — they are lovely — but a bread or biscuit that has been brushed with bacon grease is something we should all experience.
I might love cooking with bacon grease even more than I love eating bacon. It’s hard to say; I love both things a lot and am prone to emotional fluctuations. One thing I do know for certain is that only a fool tosses out bacon grease (and only a societal menace pours it down the drain). A smart person saves the grease, hoards it, and then uses it to make extremely flavorful homemade mayo, salad dressings, and perfect fried eggs; and geniuses smear them on the tops of biscuits before they go in the oven.
It adds a nice bit of colour and shine, but the smoky, salty, meaty flavour is what it’s all about. Biscuits are the most natural pairing, but any bready thing would benefit from a pre-oven smear of the rendered, seasoned pork fat. I’m imagining Olive Garden-style breadsticks with bacon grease, and it’s beautiful.
You can use a pastry brush, but you can also use your (washed) hands. Either way, you don’t need a lot of grease — just enough to give your bread a slight sheen — but I’d hate for any grease to get trapped, un-utilised, in pastry brush bristles.