Put the flour, yeast, sugar, salt, olive oil in a bowl and mix together.
Add the lukewarm water and bring the ingredients together either with a mixer or by hand to form a dough.
Knead the dough (with the mixer or by hand) for up to 10 minutes.
Knead in the walnuts and rosemary, and put the dough into a bowl.
Cover with a cloth and leave in a warm place until doubled - about 1½ hours
Place the dough onto a floured surface and knead for a few minutes. Halve it (or cut into quarters) and shape into rounds. Place these onto the baking trays, spaced out.
Cover and leave for 30 minutes to rise.
Pre-heat the oven to 230C/210C fan oven/Gas 8.
Brush the loaves carefully with olive oil.
Bake for 30 - 40 minutes until the loaves sound hollow when tapped on the base.
Cool on a wire rack.