Cup of Yum
1. Preheat the oven to 180°C/ 350°F. Line two baking sheets with parchment paper.
2. Cream the soft butter and sugar; this should take about 3 minutes. Add vanilla essence and stir again.170 g unsalted butter/ ¾ cup +50 g fine sugar / ½ cup + 1 teaspoon pure vanilla extract
3. Dry ingredients: In another bowl, mix flour, custard powder, and baking soda. Sift this mixture over the creamed butter and mix well again.170 g all-purpose flour / 1 ⅓ cups +50 g custard powder / ½ cup + ¼ teaspoon baking soda
4. Form about 28 walnut-sized balls. Place them on the baking sheets, leaving a little room between them, as they will expand in the oven. Score a pattern on the cookies using a fork. Press once horizontally, then once vertically.
5. Bake the cookie sheets, one after another, for about 15-16 minutes or until just very slightly golden (Note 3).
6. Cool: Leave the custard creams on the baking sheets for 5-10 minutes, then transfer to a wire rack to cool completely.

Filling:

Cup of Yum
1. Beat the soft butter until creamy. Slowly add the icing sugar and custard powder while beating continuously. Add the vanilla and beat until light and fluffy.50 g unsalted butter/ ¼ cup + 75 g icing sugar / ¾ cup + 2 tablespoons custard powder + ½ teaspoon vanilla extract
2. Spoon or pipe the filling on the inner side of half of the cookies. Cover each cookie with another cookie and press lightly.