There are two ways to do this depending on your yeast. Follow only the method that matches your yeast, then continue with the rest of the recipe.

Add the 500 g bread flour to a large bowl. Place the 9 g salt on one side of the bowl and the 5 g instant yeast on the other side so they do not sit on top of each other. Pour in the 375 g warm water and 10 g vanilla extract and mix until no dry flour remains. The dough will be very wet and sticky, which is exactly what you want, so do not add more flour. Check the back of your yeast packet for the recommended water temperature, since it varies by brand.

Warm the 375 g water to 100 to 110°F, stir in the 5 g active dry yeast, and let it sit for about 10 minutes until foamy. If it does not foam, the yeast is dead and you need to start over with fresh yeast. Add the 500 g bread flour and 9 g salt to a large bowl, pour in the yeast mixture and 10 g vanilla extract, and mix until no dry flour remains.

Cover the bowl and let the dough rest at room temperature for 30 minutes so the flour can fully hydrate before you start building structure.

With a wet hand, grab one side of the dough, stretch it up as far as it will go without tearing, and fold it over the center. Rotate the bowl a quarter turn and repeat for four folds total, keeping your hand on the top surface of the dough rather than digging in. Cover the bowl and rest 30 minutes.

Repeat the same four folds around the bowl. The dough will already feel smoother and more cohesive than it did the first time. Cover and rest 30 minutes.

Repeat the four folds one final time. If the dough still feels slack and spreads out quickly, give it a fourth set after another 30 minutes.

Cover and let the dough rise at room temperature until it has doubled in size and looks bubbly and jiggly, about 1 to 1½ hours after the final set. Watch the dough rather than the clock, because a warm kitchen moves much faster.

While the dough rises, line a 9x13 inch metal pan with parchment paper. In a medium saucepan over medium heat, combine the 115 g butter, 213 g brown sugar, 57 g heavy cream, and 1.5 g salt. Stir constantly until the butter melts and the sugar dissolves, about 3 to 4 minutes. Let it bubble for 1 more minute, then remove from the heat. Pour the caramel into the lined pan, spread it evenly into the corners, and scatter the chopped or crushed walnuts over the top. Set aside.

Melt the 85 g butter and stir in the 5 g vanilla extract. Pour into a shallow bowl for dipping.

Add the 38 g walnuts and the 107 g brown sugar to a food processor and pulse in short bursts until the walnuts look like coarse sand. Pulsing the walnuts together with the sugar keeps them loose instead of turning them into a paste. Stir in the cornstarch and cinnamon, then pour the mixture into a second shallow bowl.

Turn the dough out onto a surface lightly sprayed with oil. With oiled hands, pinch off a golf ball size piece of dough, dip it into the vanilla butter so all sides are coated, let the excess drip off, then roll it in the walnut cinnamon sugar until it is completely covered and set it into the pan on top of the caramel and walnuts. Work one ball at a time all the way through, dipping, rolling, and placing each one before you pinch off the next.

Nestle the balls right up against each other in rows as you fill the pan, about five or six rows of four across a 9x13 pan. They should be touching with very little space between them, and you will end up with roughly 24 to 30 balls depending on how large you make them.

Sprinkle any leftover walnut cinnamon sugar over the tops. Skip any leftover vanilla butter here, since the caramel base underneath is already rich and buttery enough.

Cover and let rise at room temperature for 1 to 2 hours, until the balls are puffy, jiggly, and have grown together into one pull-apart loaf. Watch the dough rather than the clock, since a warm kitchen moves faster and a cool one slower.

Preheat the oven to 375°F (190°C) with a rack in the center position, and set a sheet pan on the rack below to catch any caramel that bubbles over. Gently dimple the tops with your fingers. Bake for 30 to 35 minutes, until deep golden brown and the caramel is bubbling at the edges. The internal temperature should read 190 to 200°F. Tent loosely with foil after 20 minutes if the tops are browning too quickly.

Let the pan sit for exactly 5 minutes. Place a serving platter or sheet pan over the top, and using oven mitts, hold both together and flip quickly and confidently. Lift off the pan, peel away the parchment, and spoon any caramel or walnuts left behind back over the top.

Serve warm and pull apart.