Bay and Rosemary Custard

Substances:

• 1 3⁄4 cups heavy cream
• 1⁄3 cup sugar
• 4 sprigs rosemary
• 3 novel bay leaves, lightly smashed
• 2 eggs, plus 4 egg yolks
• 1⁄4 cup easy stout-elephantine yogurt
• 1 tsp. lemon zest
• 1⁄8 tsp. kosher salt