I drew upon these recipes as I adjusted and tested various combinations of ingredients. I think I like the egg/custard version best, simply because it scoops better later on (it remains somewhat soft)---but if you are going to eat it all the same day, the eggless version (which is what I made for the party) is easier, and perfectly delicious.
I just used regular kettle-popped popcorn since that's what I had on hand, but one of the recipes I consulted said that microwave popcorn works fine too, and in fact gives a slightly more assertive popcorn flavor to the ice cream.
3 c. whipping cream
3 c. milk (I have used 2%, but since Skim is what we usually have around that's what I usually use)
1/2 t. salt
3/4 c. sugar, divided
3 eggs (optional)
About 6 cups of popped, buttered, salted popcorn
Mix the milk, cream, salt, and 3/8 c. of the sugar (3/8 c. = 6 T.) in a large saucepan. [If doing the eggless version, add all 3/4 of the sugar now.] Add the prepared popcorn and stir. Over medium-high heat, bring the mixture just to a boil. Then turn off the heat and let it steep for 30 minutes.
After 30 minutes, strain the popcorn out of the cream using a fine-mesh strainer. Discard popcorn. Return the popcorn-infused cream to the saucepan.
If using eggs, in another bowl, combine the remaining 3/8 c. sugar and 3 eggs. Beat vigorously with beaters or wire whisk until mixture reaches the ribbon stage. While still whisking, slowly drizzle in 2 cups of the still-warm popcorn-infused cream. Then return the whole thing (eggs and cream) back to the saucepan with the rest of the infused cream. Over medium heat, cook until the mixture thickens slightly and coats the back of a spoon.* Remove from heat, put a piece of plastic wrap on the surface (so a skin won't form), and refrigerate until chilled.
If NOT using eggs, refrigerate popcorn-infused cream until cold.
When the cream is cold (let it chill probably at least 2 hours, or even overnight), pour it into the ice-cream maker and freeze as usual. Serve immediately for soft-serve ice cream, or put in freezer for a few hours if you want more scoopable ice cream.
*I heard someone complaining about this phrase recently, saying "Liquids ALWAYS coat the back of a spoon!" I think the distinction is that a thickened custard will stay on the back of the spoon for a minute before beginning to drip off. Like this:
Not coating spoon
Now, a note about the caramel sauce: I've been making caramel since I was (practically) on my mother's knee. I've tried many different caramel recipes, and they fall into two types: those that start with a pure melted sugar which then caramelizes and has other ingredients added at the end, and those that start off by mixing together several ingredients (butter, cream, sugar, sometimes corn syrup) and cook till thickened. As far as I can tell, both types can turn out well, but the melted-sugar version is a lot more finicky and hard to get right. You have to let the sugar melt without burning, and then treat it with extreme care so it won't seize (i.e. turn suddenly hard and crackly) when adding your other ingredients. I'm not sure what the attraction of this method is (although it is interesting to see plain sugar magically become caramel), since the two types taste identical at the end of the process. Obviously, I prefer the mix-together-at-the-beginning method. For this recipe, all you have to do is melt the butter, add sugar, salt, vanilla and cream, bring to a boil, and simmer till thickened. It's very worry-free.
Salted Caramel Sauce
1/2 c. butter
1 c. brown sugar
1/2 c. cream
1 t. vanilla
1/2 t. salt
Melt butter in saucepan. Stir in rest of ingredients and bring to a boil over medium-high heat, stirring constantly. Simmer, still stirring, until thickened.**
**I have a note on my recipe that says, "This takes 15-17 minutes." But today as I was making it again, it seemed thick enough after 10 minutes. So there's obviously some room for adjustment. Cooking it longer will yield a thicker, darker, smokier-tasting caramel, while a shorter time produces a thinner, more buttery caramel. Both are delicious, I hasten to add.)