half a vanilla bean, sliced lengthwise and scraped
1tablespoonLyle's Golden Syrup , (or corn syrup, or honey)
1/4cupheavy cream, plus 1/4 cup
2tablespoonsbourbon , (such as Bulleit)
1/2teaspoonflaky salt such as Maldon , (or 1/4 teaspoon fine salt)
Roast the bananas:
Preheat the oven to 400ºLay the bananas in a baking dish (a shallow loaf pan works well). Dot with the butter and sprinkle with the sugar. Roast in the oven until very soft, 20 minutes. Mash the bananas, and continue to roast until caramelizing around the edges, another 20-30 minutes. Remove from the oven and let cool slightly.
Make the ice cream base:
In a medium, heavy-bottomed saucepan, heat 1 1/2 cups of the half and half over medium heat until hot and steamy, swirling the pot occasionally to prevent it from scorching on the bottom.
Meanwhile, whisk together the egg yolks, sugar and salt in a medium bowl set on a damp kitchen towel.
Set a fine-mesh strainer over a large bowl or pitcher, and add the cold heavy cream and remaining 1/2 cup of half and half to the bowl. Set aside.
When the half and half is warm, slowly drizzle half of it into the egg yolk mixture, whisking constantly. Pour the yolk mixture back into the pot. Add the roasted bananas and their juices. Place the pot over a medium-low flame and cook, stirring constantly with a heat-proof silicone spatula, until the mixture reaches 170ºF on an instant read thermometer; don't let it boil. The custard will seem thick, so taking its temperature is ideal. Otherwise, look for the custard "sticking" (forming a film othe bottom of the pot, or thickening enough so that when you dip a wooden spoon into it, then swipe the spoon with your finger, your finger leaves a clear trail on the spoon.
Immediately strain the custard mixture through the strainer and into the bowl. Work the banana through the strainer with a flexible spatula or the back of a ladle, leaving the fibrous banana bits in the strainer. Discard the banana pulp. (Optionally, strain the custard a second time through an extra-fine mesh strainer, also called a chinois.) Cover the custard and chill until very cold, 2-4 hours or up to a couple of days.
Make the butterscotch sauce:
In a medium, heavy-bottomed saucepan, combine the butter, brown sugar, vanilla bean and scrapings, Lyle's syrup, and 1/4 cup of the heavy cream. Bring the mixture to a boil, stirring gently just once or twice. Simmer the mixture for 3 minutes. Remove the sauce from the heat and stir in the remaining 1/4 cup cream. Strain the sauce into a heatproof bowl or jar, then stir in the bourbon the flaky salt. Cool the sauce to room temperature, at least an hour before layering it with the ice cream, or chill in the refrigerator for up to a month. (If chilled, re-warm to a drizzle-able consistency before layering.) You should have about 1 cup of sauce.
Finish the ice cream:
Place a large (9x5" or largeloaf pan in the freezer.
Stir the rum into the ice cream base. (Optionally, put the base in the freezer for 30 minutes to get it really cold, stirring every 10 minutes. This will make for a smoother, denser ice cream that churns more quickly, thus incorporating less air.) Churn the ice cream in an ice cream maker according to the manufacturer's instructions.
Working quickly, spread 1/3 of the ice cream in the bottom of the loaf pan. Drizzle with 1/4 of the butterscotch sauce. Repeat with two more layers of ice cream and butterscotch sauce. For the top layer, drop spoonfuls of butterscotch atop the ice cream, then swirl with a toothpick. You'll have some butterscotch sauce left over to drizzle over bowls of ice cream; store this in the refrigerator, rewarming it as you're ready to serve it.
Freeze the ice cream until firm and scoopable, about 2 hours. When firm, press a piece of parchment paper directly onto the surface of the ice cream to prevent ice crystals from forming, then wrap snugly with plastic wrap. The ice cream will keep for up to a month or two.
I made this ice cream base a bit lighter and less sweet than usual; the trade-off is ice cream with a slightly icy texture. For a smoother ice cream, swap the extra 1/2 cup of half and half for the same amount of heavy cream, and increase the sugar in the custard to 1/3 cup.For the best flavor, use bananas that are yellow with lots of brown freckles.If you don't have half and half, you can use 1 cup whole milk to make the custard, and 1 1/2 cups heavy cream to finish it.Nutritional values are based on one of eight servings.