I do love good sourdough. But for me it’s always appealed to my savory side; fresh hot sourdough slathered in butter, rolls used to sop up gravy or sauce from the main dish, slices of the bread to make a great sandwich with leftover prime rib or turkey, etc.
But lately I’ve been seeing ads and recipes for using sourdough to make sweet products. Sourdough doughnuts, waffles, sugar cookies, pastries, and more. Sadly I’ve not been in a position to sample said stuff directly, or I’d have jumped at the chance.
So I ask here. Anyone have insight and experience into using sourdough to make classic sweet bakery treats?
Sourdough pancakes are fantastic. I imagine sourdough waffles would be about as good.
I can’t imagine what sourdough sugar cookies would be like. Sugar cookies are made with chemical leavening like baking powder or baking soda. Sourdough is a yeast leavening, which requires more moisture than you’d want in a sugar cookie. The result would probably be soft and cakey.
I recall bakers feed yeast with sugar? I remember remember that from cooking shows and high school chemistry.
I buy King’s Hawaiian sweet rolls several times a year for holiday meals. I love them, too much. 
I can’t recall seeing a sourdough sweet roll.
These items are just flavoured with the unfed starter, not leavened by it. You don’t add enough starter, or give enough time, or, as you say, sufficient moisture, to allow the yeast to do all that much. But the starter itself gives a bit of sourness and umami notes to your finished product.
I like to make crackers with my excess starter. When I feed Steve, I end up with a jarful. I put a few spoonfuls in the fridge for next time, use a teaspoonful for the recipe, and the rest I chuck into whatever else I’m making. Or crackers. Sourdough Crackers Recipe | King Arthur Baking
This is a recipe for using up batter-type starter – Steve is a much stiffer Euro-style starter, so I water him down 50:50 for this purpose. I also roll it out in the pasta roller on my mixer. Done in a snap!
That may be so, but there’s a ton of recipes out there for ‘sourdough sugar cookies’. They all call for sourdough starter. Here’s a typical example: https://whatscookingamerica.net/Cookie/SourSugarCookies.htm
I don’t currently keep a starter (it has a nasty habit of dying on me). When I do keep a starter, one of my favorite recipes is Sourdough Chocolate Cake. My father got the recipe from issue of Yankee magazine from the late 1970s. It’s not raised by the action of the microbes fermenting carbohydrates the way sourdough bread is. The sourdough is there to provide acid for the baking soda to react with, and also for flavor.
SOURDOUGH CHOCOLATE CAKE
1/2 cup sourdough starter
1 cup whole milk
1-1/2 cups flour
1/2 cup shortening
1 cup sugar
1/2 teaspoon salt
1 teaspoon vanilla
1 teaspoon cinnamon
1-1/2 teaspoons baking soda
2 eggs
3 ounces unsweetened chocolate, melted
Combine starter, milk, and flour and leave about three hours in a warm place until bubbly and there is a clean sourdough odor. In a separate bowl, cream shortening, sugar, salt, flavorings, and soda. Add eggs one at a time, beating well after each addition. Combine creamed mixture and chocolate with sourdough mixture. Mix at low speed until well blended. Pour batter into two greased and floured round layer pans. Bake at 350 for 25 minutes or until done. Cool and frost with icing of your choice.