Combine Flour and Yeast: In a large mixing bowl or the bowl of a stand mixer, whisk together 4 1/2 cups of the whole wheat flour with the yeast. Pour in the warm water and stir everything until just combined. Cover the bowl with a clean towel or plastic wrap and let it rest for 15 minutes. This step allows the flour to hydrate and kickstarts the yeast activation.
Add Remaining Ingredients: After resting, add the vital wheat gluten, salt, melted butter, honey, and Greek yogurt to the dough mixture. Mix well to combine all the ingredients evenly.
Incorporate Remaining Flour and Knead: Gradually add 1 1/2 cups of flour to the bowl, mixing continuously. Keep an eye on the dough’s texture; it should start pulling away from the sides of the bowl, forming a slightly sticky but elastic mass. Add more flour sparingly if necessary. Knead the dough using your stand mixer’s dough hook for about 5 minutes, or knead by hand for 10 minutes until it feels smooth and elastic.
Prepare Baking Pans: Spray two loaf pans with non-stick cooking spray and line the bottoms with parchment paper for easy bread removal.
Shape the Dough: Turn the kneaded dough out onto a lightly floured surface. Divide it into two equal portions. Flatten each portion into a rectangle approximately 9 inches long. Roll each piece tightly into a loaf shape and place them seam side down in the prepared pans.
Proof the Dough: Cover the pans with a lightweight kitchen towel and allow the dough to rise in a warm place until it has puffed up and rounded over the top of the pans, about 1 hour. For a quicker rise, see notes below.
Bake the Bread: Place both loaf pans on the middle rack of a cold oven. Set the oven temperature to 350°F (175°C) and bake for 30 to 38 minutes, until the bread tops turn golden brown.
Finish and Cool: Remove the pans from the oven. While the bread is still hot, spread a thin layer of cold butter over the crust for extra flavor and softness. Carefully invert the loaves onto a wire rack and let them cool completely before slicing.