Using a double boil method, dissolve cheddar cheese with butter, then add in milk. Set aside to cool.
Sieve flour into a mixing bowl, add in egg yolks and cooled melted cheese and butter mixture.
Whisk on medium high speed until creamy and ingredients are well combined. Set aside and preheat the oven at 150 degrees C.
In another clean bowl, whisk egg whites until frothy, add in cream of tartar. Continue beating and gradually add in sugar in 3 batches. Whisk on medium high speed until stiff peaks form.
Pour half meringue into egg yolk mixture. Mix well. Then pour in there remaining meringue and continue mixing.
Pour batter into a lined loose bottom 7" round cake tin. Smooth the surfacewith a use of spatula. Steam in baking tray.
Bake in a preheated oven at 150 degrees for 70 minutes. Remove from pan immediately to cool on rack.