few days ago I made RLB's muffins described in her book "the bread bible", with several adaptions. I used these ingredients:
-60 gr unsalted butter
-1 large egg
-100 gr caster sugar
-1 teaspoon of baking powder (sodium pyrophosphate + sodium bicarbonate, I guess it's single- and slow acting)
-135 gr of flour mix (I choose 45 gr of potato starch and 90 gr of cake flour)
-100 gr of quark instead of sour cream
-100 gr of raisins
-a touch of salt
-a teaspoon of dried and grated orange zests
Disclaimer. You will think that I didn't prepare muffins. Yes I know, but it doesn't matter. My point is another.
I left all ingredients at room temperature for several hours. Keep in mind that in this period of the year my apartment reaches 31°C if not more...with horrible humidity levels.
Using only a tablespoon I stirred together butter, salt and sugar until I obtained a cream, than I added the egg and stirred more. Already at this point the cream became quickly very firm, like a stiff foam. I stirred in the baking powder and the zests, then the starch and finally the remaining flour alternated with the quark. The more I stirred the more the batter rose in volume and increased in firmness. Overall I mixed the ingredients for no more than 10 minutes.
Does it always work like this with those ingredients? It was my first time with muffins and I didn't expect such a strange behaviour. It was as if I had added stiff egg-whites. Some friend suggested that the baking powder can have started its job in advance, but since this is a slow-acting powder the solution doesn't convince me. Moreover it wouldn't explain such a massive increase in viscosity.