5 tbsp. salted butter, melted (or unsalted butter plus ¼ tsp. salt)
1/3 cup packed light brown sugar
¼ cup flour
½ tsp. vanilla extract
¾ cup chocolate chips (I used mini chips)

For the ice cream:
3 tbsp. unsalted butter
2 cups heavy cream
2/3 cup dark brown sugar
4 large egg yolks
Pinch of coarse salt
2 tsp. vanilla extract
1½ cups whole milk
1 cup chocolate chips (semisweet or bittersweet)