Bananas Foster Custard Shake
By Marty Cole · June 4, 2026
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Creamy, cold, and just barely scoopable, that first spoonful of this Bananas Foster Custard Shake from the Ninja Slushi honestly stopped me mid-bite. The egg yolks and heavy cream give it this custardy weight, and the brown sugar syrup pulls it all toward caramel territory without being cloying. My wife took one taste and quietly moved the cup away from me, which is the highest compliment in our house. Practical tip: use a genuinely ripe banana, like spotted-all-over ripe, because an underripe one just tastes starchy and flat once it's churned through. The machine does the rest in about 40 minutes.
Your machine size
Slushi 64 oz (Standard) · quantities scaled ×1
💡 Serve within 30 minutes
High-fat dairy can churn into butter under long agitation. Dispense and enjoy soon after it's ready.
Ingredients
- Heavy Whipping Cream9 oz
- Whole Milk4 oz
- Ripe Banana1 whole
- Brown Sugar Simple Syrup3 oz
- Egg Yolks2 yolks
- Unsalted Butter1 tbsp
- Vanilla Extract0.5 tsp
- Ground Cinnamon0.25 tsp
- Table Salt0.13 tsp
- Whipped Creamoptional1 garnish
Makes ~22 oz
Directions
- 1Melt the butter in a small skillet over medium heat, add the sliced banana and cook 2 to 3 minutes until softened and caramelized.
- 2Whisk the egg yolks and the brown sugar simple syrup in a bowl until smooth.
- 3Heat the cream with the cinnamon until barely simmering, then temper the yolks by slowly whisking in half the hot cream.
- 4Return everything to the pan and cook on low, stirring, until the custard coats the back of a spoon.
- 5Remove from heat, add the caramelized banana, milk, vanilla, and salt. Puree until completely smooth, then refrigerate until fully chilled.
- 6Pour the cold custard base into the Slushi, select MILKSHAKE, raise coldness to level 10, and run for 25 minutes until thick and creamy.
Tips
- Use ripe bananas with brown spots for the best flavor and natural sweetness in your custard base
- Pour your liquid base into the Slushi bowl at room temperature, not chilled, so the machine can properly churn and freeze it
- If your shake comes out too icy rather than creamy, you likely have too much liquid relative to cream and egg yolks, so adjust your ratio next time
Variations
- Swap the cinnamon for nutmeg and add a splash of dark rum for a grown-up version
- Use brown butter instead of regular unsalted butter and skip the vanilla for a deeper, more nutty flavor
FAQ
- Can I make this without egg yolks?
- It won't have the same custard richness, but you can replace them with 1/4 cup of sweetened condensed milk for body and creaminess.
- Why didn't my shake freeze into slush consistency?
- The Slushi machine needs enough time to churn and freeze, usually 40-60 minutes depending on your kitchen temperature, so be patient and don't rush it. Also check that your base isn't too warm when you pour it in.
- Can I store leftovers?
- Yes, pour any leftover base into an airtight container and refrigerate for up to 2 days, then run it through the Slushi machine again when you're ready to drink it.
- Is there a dairy-free option?
- You can substitute heavy cream with full-fat coconut cream and whole milk with oat or cashew milk, though the texture will be slightly less creamy without the egg yolks.
Nutrition
Per serving · makes about 2 servings · estimated
Ratings & Reviews
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Meet Marty Cole
I'm a home cook who got a little obsessed with the Ninja Slushi and Creami. I test every recipe in my own kitchen on a real machine, dial in the texture, and only post the ones my family actually finishes.
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