In a large bowl, combine flour, granulated sugar, salt, milk, egg, sourdough starter, and softened butter.

Stir until it comes together as a shaggy dough.

Knead the dough by hand (8–10 minutes) or in a stand mixer (5–6 minutes) until it feels smooth and elastic.

Shape the dough into a ball, cover it, and let it rise in a warm spot (75-80°F) until it doubles in size (about 4–6 hours, or longer if your kitchen is cool).

In a small bowl, mix granulated sugar, brown sugar, cinnamon, and 2 teaspoons of flour. Set it aside.

Lightly dust your counter with flour. Roll the dough into a rectangle, about 12 x 22 inches (30 x 55 cm).

Brush the entire surface with softened butter and then generously sprinkle the cinnamon-sugar mixture evenly over the buttered dough.

Starting from one long side, roll the dough into a tight log.

Use unflavored dental floss (or a sharp knife) to cut it into 8 large rolls or 12 smaller rolls. Leave the rolls on the counter for a few minutes while you prepare the caramel.

Grease a 9x13 inch baking dish.

In a small saucepan, melt the butter over medium heat.

Add cream, brown sugar, and maple syrup.

Stir and let it gently simmer for 3–4 minutes, until it coats the back of a spoon.

Remove it from the heat and stir in a pinch of salt.

Pour the hot caramel glaze into the greased baking dish.

Sprinkle the chopped pecans evenly over the glaze.

Arrange the cut rolls on top of the caramel and pecans.

Cover the dish and let it rise in a warm spot (75-80°F) until they are puffy and the dough springs back slowly when gently pressed (about 2–4 hours).

Preheat the oven to 350°F and bake the rolls for 30–35 minutes, until they turn golden brown and the caramel is bubbling.

While the dish is still hot, place a parchment-lined baking sheet over the top of the pan.

Carefully (with oven mitts!) flip the whole thing upside down so the rolls release onto the sheet and the caramel-pecan topping drips over them.

Let them cool for 10 minutes before serving. Serve warm.