The sour cream-enhanced dough for these rich, tender buns is a real pleasure to work with, particularly after its overnight refrigeration.
To make the dough: Warm the sour cream gently, and combine it with the sugar, salt, and butter in a large mixing bowl, the bowl of an electric mixer, or the bucket of your bread machine.
Cool the mixture to lukewarm (if it isn't already that temperature). Weigh your flour; or measure it by gently spooning it into a cup, then sweeping off any excess. Add the yeast, warm water, eggs, and flour.
Mix and knead the dough, using your hands, a mixer, or a bread machine, until it's soft and smooth.
Transfer the dough to a lightly greased bowl, cover the bowl with plastic wrap, and refrigerate the dough overnight.
Next day, remove the dough from the fridge, and divide it into about 20 pieces, each 1 3/4 ounces, about the size of a golf ball.
Place the pieces on lightly greased or parchment-lined baking sheets, leaving about an inch between them.
Flatten the balls until they're about 1/2" thick, cover them with lightly greased plastic wrap, and allow them to rest for 10 minutes.
To make the pineapple filling: In a medium-sized saucepan, heat the drained pineapple to boiling.
If you're using ClearJel, mix it with the sugar, and stir this mixture into the pineapple.
Immediately remove the filling from the heat, and stir in the melted butter. Cool to lukewarm before using.
If you're using cornstarch, mix it with the reserved pineapple juice. Stir the dissolved cornstarch and sugar into the hot pineapple, and cook over medium heat, stirring, until the mixture thickens and becomes clear.
Remove it from the heat, stir in the melted butter, and let it cool to lukewarm before using.
To make the streusel topping: In a small bowl, mix together the flour and sugar, then add the butter, stirring until crumbs form.
To assemble the buns: Using your fingers, make a wide, deep indentation in the center of each flattened dough ball. Don't be afraid of being decisive here; you want to make a deep enough indentation that it doesn't just disappear as the buns rise and bake.
Place about 1 tablespoon of the filling into each bun; crumble a little of the streusel on top. Cover the kolaches, and allow them to rise for about an hour; they won't necessarily double in bulk.
Uncover the kolaches, and bake them in a preheated 350°F oven for 15 to 20 minutes, until they're golden brown.
Remove the kolaches from the oven, and serve warm, or at room temperature. Store any leftovers airtight at room temperature for several days; freeze for longer storage.
