Preheat oven to 350°F (177°C). Line a 9 x 13 inch baking pan with parchment paper.
Add in the flour and sugar to mixing bowl of stand mixer and mix on low speed until combined. Add in melted butter and 1 1/2 cups of water. Beat on high speed until no lumps remain. Be careful not to overmix, it shouldn't take very long. Then add in the remaining water and beat on low medium speed until evenly mixed in.
Bake for about 35 minutes or until toothpick inserted comes out clean. Cake surface will remain pale (it will only brown a little around the edges). If adding frosting, wait until cake is fully cooled before frosting.
Notes
Homemade self-rising flour: add 3 1/2 cups all purpose flour, 5 1/4 tsp baking powder and 7/8 tsp salt to a bowl. Whisk until evenly combined.
When measuring out the flour (for either all purpose flour or self-rising flour), make sure to use the spoon and level method. This means that you should spoon the flour into the measuring cup and then level off the top with a knife. Do not directly dip your measuring cup into the flour because this results in too much flour being added.
Water amount: Depending on the self-rising flour brand you use, you may need to add more liquid. I used Lily's self-rising flour which has 2 grams of protein per 1/4 cup. If your self-rising flour has 3 grams of protein per 1/4 cup (or the all purpose flour you are using to make self-rising flour has 3 grams), then you will need to add 5 oz more of water. If you are using the higher protein flour, add the full 2 cups of water initially to the batter (instead of 1 1/2 cups) and then add the remaining 5 oz after you have a smooth batter and no lumps.
I frosted the cake with a whipped cream frosting. You can also use whatever frosting you prefer.
Optional Whipped Cream Frosting: Add 2 cups of cold heavy cream and 6 tbsp of sugar to a large mixing bowl. Beat on highest speed until soft peaks form. Spread over the surface of the cake. Make sure the cake has already cooled before adding the frosting.
The estimated nutrition does not include the whipped cream frosting.
The nutrition information provided are only estimates based on an online nutritional calculator. This is not a comprehensive list of all the nutrients in the recipe (i.e., does not include vitamins, cholesterol, etc). I am not a certified nutritionist. Please consult a nutritionist or doctor for accurate information and any dietary restrictions and concerns you may have.