In a saucepan, heat the heavy cream and whole milk until steaming, not boiling, then turn off the heat when steam is clearly rising. Visual cue: tiny bubbles begin at the edges and the surface looks steamy.

In a bowl, whisk the egg yolks with the granulated sugar until smooth and slightly thick. Slowly pour the steaming cream mixture into the yolks while whisking constantly to avoid scrambling.

Return the mixture to the saucepan and cook, stirring constantly, until it reaches 175°F. Visual cue: the custard coats the back of a spoon and looks glossy.

Strain the custard into a clean container to remove any bits of cooked egg. Visual cue: the strained liquid flows smoothly.

Stir the strained custard with butter extract, vanilla extract, almond extract, and salt until fully combined, then cool to room temperature. Visual cue: the base becomes evenly colored, pale golden, and silky.

Cover and refrigerate for 4 hours until thoroughly chilled. Visual cue: the custard feels cold throughout with no warmth in the center.

Churn the chilled base in an ice cream maker according to the manufacturer’s instructions until it reaches a soft-serve consistency. Fold in the rainbow sprinkles during the last 2 minutes of churning so they stay suspended.

Transfer to a freezer-safe container and freeze until firm. Visual cue: the ice cream becomes scoopable and holds a shape, then serve with more rainbow sprinkles.