In a large bowl or in a stand mixer like this, combine the "sourdough sponge" ingredients. Allow this sponge to sit for 20-30 minutes to encourage fermentation. Please note: the yeast is optional. If you have a well fed and tended sourdough starter it should offer all the lift you need to raise your bread. Meanwhile, add garlic and olive oil to a pan over medium heat, Sautee, stirring constantly, until the garlic is fragrant. Add greens by the handful, stir, and cook until all greens are well wilted. Remove from heat.
Add garlic and greens mixture, cubed cheddar and salt to the sourdough sponge, Stir well to combine.
While mixing, start adding flour by the half cup full until it forms are cohesive ball. The bread with still be somewhat sticky at this point.
Turn the dough out onto a well floured surface and knead, adding flour as necessary, until you have a springy, elastic loaf. The dough should be soft, but no longer sticky at this point.
Transfer dough to medium sized bowl greased bowl and cover with a towel or plastic film. Allow the dough to rise until doubled in volume - about 1.5 hours.
After first rise, gently "punch down" and reform the dough ball. Line the bowl with a generously sized sheet of parchment paper. Place the dough in one the paper, cover, and let rise until doubled in volume again. This rise may be slightly faster than the first.
Place your dutch oven in a cool oven and adjust the heat to 450 degrees F. When the oven is fully preheated, score an X into the top of the loaf with a sharp instrument. Remove the lid from the dutch oven and lift the dough gently out of the bowl using the parchment sling. You may choose to lightly spritz the loaf with water for a crustier exterior at this time. Replace the lid and shut the oven door. Bake the bread in the dutch oven for 25 minutes. Remove cover and cook for an additional 10-12 minutes until the bread is deeply golden amber in color and sounds hollow when tapped.
Remove bread from dutch oven using the parchment sling. Remove bread from parchment and cool completely on a wire rack before slicing.