Homemade Tim Tams

unsalted butter (at room temperature (115 g))

granulated sugar ((1/2 cup, or 115 g))

egg (at room temperature)

unsweetened Dutch-processed cocoa powder ((1/3 cup, or 30 g))

all-purpose flour ((1 cup, or 150 g))

salt

unsalted butter (at room temperature (115 g))

powdered sugar ((1 cup, or 115 g))

unsweetened Dutch-processed cocoa powder

malted drink powder ((like Ovaltine or Horlicks))

milk or dark chocolate ((280 g))

coconut oil