Preheat the oven to 350ºF and line 2-3 baking sheets with parchment paper.

In a large mixing bowl, whisk the melted butter and brown sugar together.

Whisk in the molasses, eggs, and vanilla.Mix the dry ingredients with the wet ingredients.

Fold in the oats, followed by the walnuts until incorporated.

Form uniform sized balls of dough and flatten them out with a wet glass bottom to control the shape.

Bake for 10 minutes and cool on a rack.

Heat the milk in a heavy bottomed saucepan over medium to medium-low heat. Stir the milk occasionally to prevent it from scorching.

In a mixing bowl, beat the sugar, eggs, and vanilla together until it turns a pale shade of ivory.

When the milk reaches a simmer, ladle in a spoonful of hot milk into the egg mixture and whisk it in right away to prevent the eggs from curdling. Ladle in half of the milk, whisking it in.

Pour the egg mixture into the saucepan and continue to heat over medium to medium-low heat, stirring constantly to prevent scorching. As you stir, you may notice a subtle change in the weight of the milk. This means you can start testing for doneness by coating the cooking spoon in cream, holding it horizontally and running a finger through the centre. If a clear line forms and it doesn't disappear, the crème anglaise is ready and may be removed from the hot element.

Once it's cooled, run it through a sieve and then pop it in an ice cream maker until it's stiff.

Prepare the cookies by turning them upside down.

Transfer the ice cream to a piping bag and swirl a generous amount of ice cream onto half of the cookies.

Place the top on each filled cookie to complete the sandwich.

Move them to the freezer to firm them up and then wrap them in wax paper and store in a freezer bag.