This is lifted from Chef Steps.
||egg yolk (~1)
- Preheat a water bath to 68°c.
- Prepare 5–6, 8 oz canning jars. Make sure they’re clean and the lids are off.
- Chop butter into chunks and heat butter in microwave on high until boiling (about 2 minutes). Set aside to cool.
- In a skillet over medium heat, cook bacon, onions, and shallots until soft and translucent.
- Add brandy to the pan and boil for about one minute, stirring occasionally. It may catch on fire, have a wet tea towel ready.
- Turn off heat and let rest for about 10 minutes to infuse flavors.
- Strain reduction through a fine-mesh strainer and, using a spatula, press down to extract most of the liquid from the strainer. You should wind up with about 250 g of liquid.
- Wash your strainer, you’ll need it again in a rush.
- In a blender, combine liquid with all other ingredients except butter. Blend just until smooth—we want to avoid cooking the livers during this step.
- Once livers are thoroughly blended, slowly add butter while continuing to blend to keep the mixture emulsified. Heating the butter should’ve made it separate—pour only the clarified butter, leaving the white milk solids behind.
- Working quickly, pass the purée through a fine-mesh sieve. (It’s important to be speedy so that your spread doesn’t begin to oxidize).
- Transfer purée to canning jars. Twist the lids until “fingertip tight”, meaning just barely closed and still possible to open with your fingertips.
- Lower into water bath with tongs and let cook for 90 minutes.
- When it’s almost cooked, prepare an ice bath to chill it.
- Once it’s cooled down you can tighten the lids and store in the fridge.