Preheat oven at 170C / 338F with top and bottom heating with fan setting.
Coat a cake pan (I used a 9-inch square cake pan) with butter from the butter wrapper, dust with plain flour and knock off the excess plain flour. Set aside.
In a separate bowl, whisk together 200g plain flour, 1.5 tsp baking powder and 1 tsp fine salt.
200 g plain flour, 1.5 tsp baking powder, 1 tsp fine salt
Cream 170g unsalted butter in a food mixer with paddle attachment on high speed.
170 g unsalted butter
Gradually add 150g Stevia sweetener (or sugar, you can opt to increase the sugar volume up to 225g) and mix until the mixture is pale and fluffy, about 4-5 minutes.
150 g Stevia sweetener
Add eggs one at a time and beat on medium low speed until incorporated before adding the next egg. Scrape the sides and bottom of the bowl with a rubber spatula to ensure even mixing.
2 medium eggs
Add 1.5 tbsp vanilla extract and mix on medium until incorporated.
1.5 tsp vanilla extract
Sift 200g plain flour, 1.5 tsp baking powder and 1 tsp fine salt into the batter in 3 rounds, alternating with 170ml fresh milk.The sequence will be: dry ingredients > milk > dry ingredients > milk > dry ingredients.Mix on low speed until the ingredients are incorporated each round. Do not overmix. Beat until no signs of flour. Scrape the sides and bottoms of the mixing bowl with a rubber spatula to ensure even mixing.
200 g plain flour, 1.5 tsp baking powder, 1 tsp fine salt, 170 ml fresh milk
Pour the batter into the cake pan and level the top with a rubber spatula. Tap a few times on the table and use a chopstick or toothpick to swirl around the batter to release any air bubbles.
Bake at 170C / 338F for about 25-30 minutes. If you are using an oven without fan, you may need to bake it for about 35-45 minutes. Test for doneness by using a chopstick or toothpick to insert into the centre of the cake. If it comes out clean, it is ready. Test again by gently poking the surface of the cake with your finger, if it is springy, you can remove the cake from the oven.
Let the cake cool in the pan for at least 15 minutes on a cooling rack before removing it from the pan. Enjoy!