Note: Wait until you've made the biscuit dough before you heat your oven.
Measure out the flour and Ovaltine powder and pour them into a large bowl. Add the yellow sugar, ⅛ cup of granulated sugar, baking soda and salt and whisk everything together.
Melt the butter in a microwavable container and leave to cool for a couple of minutes.
Make a well in the centre of the flour mixture and pour in the cooled melted butter and the egg and using a fork, whisk until egg is lightly beaten. Then using a rubber spatula, fold the butter and eggs into the flour mix. Fold in the chopped Maltesers and leave the dough to sit on the counter while you heat the oven.
Place your oven racks in the middle of the oven and heat to 350°F (180°C).
Line the cookie sheets with parchment paper and fill a shallow bowl or plate with the remaining ½ cup of granulated sugar. Scoop out the dough in 1 tablespoon amounts and roll gently into balls. Drop the balls into the sugar and roll them around until they are coated and place each ball onto the cookie sheets. You'll want to spread the balls out as the dough spreads while it's baking. 8 balls to a cookie sheet is a good fit. Lightly flatten each ball with your palm and then place the cookie sheets in the oven.Rotate the cookies sheets halfway through the baking time. If you're baking 2 sheets at once, rotate the sheets from top to bottom rack and back to front. The biscuits will take around 15 minutes to bake. Make sure to check them before the 15 minute mark as each oven is different when it comes to baking times. Look for the cookies to be light golden on top and crackled on top.Continue to bake the remaining dough in the same way. You should end up with around 30 biscuits. Let the cookies cool on a cooling rack before serving.