Whisk together 4 egg yolks with 3/4 cup sugar until the mixture turns pale and thick—this takes about 3 minutes of continuous whisking. You're creating an emulsion base that prevents ice crystals later, so don't rush this part. I used to skip the pale stage entirely until Connor pointed out the texture difference when we made blueberry swirl ice cream family summer side-by-side with rushed versions.

Heat 2 cups milk and 1 cup heavy cream in a saucepan until steam rises, but don't let it boil. This should take 4-5 minutes on medium heat. Temperature matters because you're about to combine this with raw eggs, and you need heat to safely pasteurize them without scrambling.

Temper the egg mixture by adding hot milk one ladle at a time while whisking constantly for 30 seconds between each addition. Add 3 ladlefuls total, then pour the entire egg mixture back into the saucepan with the remaining milk. Why this step? The gradual heat transfer prevents the eggs from cooking into scrambled bits—I learned this the hard way by skipping it once and ending up with cottage cheese texture.

Cook the custard over medium heat, stirring constantly with a wooden spoon, until it coats the back of the spoon—about 7-8 minutes. The mixture should reach 170°F on an instant-read thermometer. Strain through a fine-mesh sieve into a bowl, then stir in 1 tsp vanilla powder, 1/4 tsp salt, and 1 tbsp lemon juice.

Cool the custard completely in the refrigerator for at least 2 hours. Cover the surface with plastic wrap pressed directly onto the custard so no skin forms. This step isn't optional—warm or room-temperature custard won't set properly in the freezer.

Pour the cold custard into a 9x13 baking dish and freeze for 2 hours until the edges are firm but the center is still soft. Remove and stir vigorously with a fork, breaking up ice crystals that formed around the edges. Return to the freezer.

After another 2 hours, remove again and repeat the stirring process. This is when Lily takes over and drizzles the 1/2 cup blueberry puree mixed with 2 tbsp honey in ribbons across the top, then swirls it with a butter knife—this prevents over-blending and keeps those stunning purple streaks intact.

Freeze for a final 1-2 hours until firm enough to scoop. Top with 1/2 cup chopped pistachios and 1 tsp lemon zest when serving, which adds a bitter-sweet contrast that makes every bite interesting instead of just sweet.