Ingredients

For the banana purée

• 6 ripe bananas

For the ice cream base

• Glucose syrup (5%) 50g | ¼ cup
• Brown Sugar (15%) 150g | ¾ cup
• Cream (30%) 300g | 1 ½ cups
• Milk (40%) 400g | 2 cups
• Egg yolks (10%) 100g | about 5 large yolks
• Cornstarch 10g | 1 tablespoon plus 1 teaspoon, mixed with 40g | 4 tablespoons of cold milk
• Creme Fraîche 100 g
• Vanilla paste 1 Tbsp
• Banana extract 15g | 1 tbsp
• Dark Rum 45g | 3 tbsp

For the chocolate swirl (Stracciatella)

• Dark Chocolate 100g
• Kosher or sea salt 3g | ½ teaspoon
• Cream 50g | ¼ cup

Instructions

For the banana purée

1. 3 hours before cooking place the frozen bananas on a rack set over a cookie sheet and let thaw. This will dehydrate the bananas and leave a lot of liquid which may need to be poured out if the bananas are very humid.
2. Cook the ripe banana coins over medium heat until substantially all of the liquid has evaporated. Do not burn. Set aside to cool.

For the ice cream base

1. Prepare an ice bath. Fill a large bowl two-thirds of the way with very icy ice water and place it in the refrigerator.
2. Boil the dairy and sugars. Put the cream, milk, glucose, and sugar in a medium heavy-bottomed saucepan, and place it over medium-high heat. Cook, whisking occasionally to discourage the milk from scorching, until the mixture comes to a full rolling boil. Whisk into the simmering dairy the cornstarch mixture and then cook for 1 minute.  Then remove the pot from heat.
3. Temper the yolks and cook the custard. In a medium bowl, whisk the yolks. Add ½ cup of the hot dairy mixture to the yolks while whisking so the hot milk doesn’t scramble the yolks. Pour the tempered yolks back into the pot of hot milk while whisking. Place the pot over medium-low heat and cook, stirring and scraping the bottom of the pot constantly with a rubber spatula to avoid curdling. Once the eggs have been tempered whisk in to the base the banana purée.
4. Chill. When you notice the custard thickening, or the temperature reaches 180°F on a kitchen thermometer, immediately pour the custard into a shallow metal or glass bowl. Nest the hot bowl into the ice bath, stirring occasionally until it cools down.
5. Strain. Strain it through a fine-mesh sieve to remove any bits of egg yolk. Then add the creme fraîche and the vanilla paste. Mix the custard with the inversion mixture until completely mixed.
6. Cure. Transfer the cooled base to the refrigerator to cure for 4 hours, or preferably overnight.
7. Whisk. Prior to churning the ice cream base, stir in the banana extract and the dark rum. Taste and adjust accordingly.
8. Melt the chocolate swirl (Stracciatella). Fill a medium pot with 2 inches of water, and place the pot over high heat until it comes to a boil, then reduce the heat to a simmer. Place the dark chocolate, milk chocolate, cocoa powder, salt and cream in a metal or glass bowl with a rim about 2 inches higher than the pot and nest it over the pot of simmering water, making sure the bottom of the bowl does not touch the water. Melt the chocolates, stirring occasionally, until smooth. Remove the bowl from the pot, wipe the bottom dry of any condensation, and set aside in a warm place.
9. Churn. Place the base into the bow] of an ice cream maker and churn according to the manufacturer’s instructions. The ice cream is ready when it thickens into the texture of soft-serve ice cream and holds its shape, typically 20 to 30 minutes.
10. Add the chocolate swirl. When the ice cream is about 5 minutes from completion, start slowly pouring into the ice cream maker the chocolate swirl. Add this slowly so it will harden as it mixes and not get integrated into the ice cream base. You will need to redirect the ice cream base away from the edge of the maker so it gets integrated to the entire ice cream and not just on the edges.
11. Harden. To freeze your custard ice cream in the American hard-pack style, immediately transfer it to a container with an airtight lid. Press plastic wrap directly on the surface of the ice cream to prevent ice crystals from forming, cover, and store it in your freezer until it hardens completely, between 4 and 12 hours. Or, feel free to enjoy your ice cream immediately; the texture will be similar to soft-serve.