Mix this up a month before Christmas (it needs to age in the fridge). Real, alcoholic eggnog made with nothing but eggs, cream, alcohol, and sugar. It's delicious.
Makes ~2 litres (plus another 2 litres added milk at the end)
In a large bowl, beat the eggs and sugar together with an electric mixer on low (avoid froth - we're not trying to whip the eggs, just mix the ingredients) until the sugar is dissolved, scraping down the sides and bottom of the bowl, about 2 minutes. Add the spirits very slowly, while beating constantly — if you add the spirits too quickly, it will curdle the eggs. Finally, beat in the cream. Bottle in clean glass jars. Store in the fridge for a couple weeks (I often get into it at one week without consequences), periodically turning the jar, gently, to mix the contents. It will separate, this is okay.
Strain through a fine sieve before serving to remove any curdled egg or egg "string" (this is a vital step, it will improve the texture immensely). Dilute 50/50 with milk and serve.
About Raw Eggs
People tend to be concerned about eating (or drinking) raw eggs. I could tell you that salmonella is incredibly rare in the modern food chain (it's true). That wouldn't reassure me much. So here's the real reason I'm willing to drink this: Alcohol. Kills. Everything. Given time - and that's why you age this for a couple weeks. This is why Europe has a history of small beer: biological agents in stream or well water could make you ill, but throw in a bit of yeast and sugar? Voila, dead microbes, even at just 1% alcohol.
Choice of Alcohol
I once used a particularly flavourful dark rum (Cruzan - great stuff, although I've only ever got it by going to the U.S.) in this mix: I expected it to dominate with its molasses-like flavour, but it wasn't even identifiable. What was identifiable was the smoke and peat of Bowmore whisky, enough so to bother some people and thrill others. I've never concerned myself with the brandy, just using cheap stuff. I've backed off the Bowmore: the vanilla and oak of a bourbon works particularly well, Bulleit or Maker's Mark are probably best. Rum is less important, but I favour Mount Gay or Havana Club. (These aren't product placements: I just know what I like.)
The eggs account for about 650 ml of liquid, making the grand total a bit over two litres. Assuming the alcohol added is all 40% (it might be 43%, but that's not going to seriously affect this approximation), this comes out at 7% alcohol in its undiluted form. After you add the milk at the end you'd be at roughly 3.5% alcohol.