Combine cream, milk, and lavender in a saucepan. Warm over medium heat until steaming, about 5 minutes. Remove from heat, cover, and steep 30 minutes to 1 hour. Strain out the lavender, pressing gently.

Return the infused cream to the pan and rewarm until steaming. Whisk yolks, sugar, and salt until thick and pale. Slowly whisk about 1 cup of the hot cream into the yolks, then pour it all back into the pan. Cook over medium-low, stirring constantly, until the custard coats the back of a spoon and reaches 170°F, about 5 to 7 minutes. Stir in vanilla if using.

Pour the custard through a fine-mesh sieve into a clean bowl. Place plastic wrap directly on the surface and refrigerate until very cold, at least 4 hours or overnight.

Churn the chilled custard in an ice cream maker until thick and soft-serve-like, 20 to 25 minutes. Transfer to a container, smooth the top, and freeze until firm, about 4 hours.

Let the ice cream soften at room temperature for 5 minutes. Scoop into bowls, drizzle with honey, and top with a few dried lavender buds. Serve right away.