Dissolve yeast in warm water in a large bowl. Let stand until creamy, about 10 minutes.

Add 2 ½ cups flour, buttermilk, eggs, 1/4 cup white sugar, 1/4 cup softened butter, baking powder, and salt to yeast mixture; stir until well combined. Stir in remaining 3 cups flour, 1/2 cup at a time, beating well after each addition. Knead dough on a floured surface until smooth and elastic, about 8 minutes.

Divide the dough in half, roll each half into a 12x7-inch rectangle, spread with butter, sprinkle with sugar and cinnamon, roll up each rectangle, and cut into 12 slices.

Coat 2 round cake pans with butter, brown sugar, pecans, and raisins. Arrange dough slices into pans, leaving space between slices. Cover and let rise until doubled, about 30 to 60 minutes.

Preheat oven to 375 degrees F (190 degrees C).