In a standing mixer, add 2 c. of flour, water, sugar, and instant yeast. Mix on low for 4 minutes using the dough hook attachment.

Add in salt and remaining flour 1 c. at a time. Once dough is all added, mix for 5-6 minutes until dough is slack (super smooth, super soft, unable to hold its shape), increasing your mixer's speed to medium. If your dough is too dry, add 1 tbsp. of water at a time until it becomes slack. 

Add in butter 1 tbsp. at a time, waiting until butter is completely incorporated before adding more butter. Mix until dough starts to pull away from the bowl and is smooth and shiny. Transfer dough to a greased, covered bowl and allow to double in size (about 1 hour). 

Punch the dough down and place on a lightly floured board. Divide dough into 4-8 pieces and shape. Try to use as little flour as possible. 

Transfer to parchment lined baking tray. Spray plastic wrap slightly with non-stick cooking spray and use to cover the hoagie dough. Allow to rise again until almost double, about 30-45 minutes. Do not overproof.

Preheat over to 375°F. If you want slashes in your bread, do so now, or brush with coating of your choice. Bake for 16-23 minutes, until golden brown. To ensure they're completely baked on the inside, temp with a thermometer. The internal temp should be 200°F. 

Allow to cool before slicing down the side.