Stir together the warm water, sugar and yeast in a measuring cup or small bowl; let stand until foamy, about 5 minutes.
In the bowl of your stand mixer attached with a dough hook, add in flour and 2 teaspoons salt; stir to distributed salt.
Pour into the mixing bowl, the proofed yeast mixture, milk and olive oil. Mix on low speed until dough comes together. Increase speed to medium and mix until dough is smooth, about 5 minutes.
Lightly grease a bowl with olive oil, place in the dough ball and turn to coat all sides. Cover with plastic film and let rise in a warm, draft-free place until doubled in size, about 1 hour.
In the meantime, in a small saucepan over medium heat, combine 2 tablespoons of chopped rosemary and 2 tablespoons olive oil. Heat the mixture until olive oil bubbles, about 1 minute. Add in chopped cranberries and toasted walnuts; remove from heat. Let cool to room temperature.
Line a baking tray with parchment paper and set aside. Once dough has risen, punch it down and knead in the cranberry/walnut mixture. (I was able to incorporate the mixture easily with a wooden spoon in the same bowl.) Form the dough into a tight ball, cover and let rest for 15 minutes.
Pat the dough onto the sheet of parchment paper. (I divided mine into two flat, round loaves on separate sheets.) Cover with a plastic film and allow it to rise until doubled, about 45 minutes.
Preheat the oven to 400 degrees F. Dimple the dough with your fingertips to make indentations. Lightly sprinkle with sea salt (don't add too much unless you like salty), if using, and fresh cracked black pepper.
Place loaf in the middle shelf of a preheated oven. Bake for 20 - 30 minutes or until golden. Cool on a wire rack. Serve warm.