Heat oven to 425 degrees F. Remove 8 walnut halves and reserve for garnish. Spread remaining walnuts on baking sheet. Toast in 425 degree oven for 6 minutes. Cool; chop. Leave oven on.
Heat 1-1/2 tablespoons oil in small skillet over medium heat. Add onion; cook 10 minutes or until softened. Stir in olives, Italian seasoning and chopped walnuts; cook 3 minutes or until fragrant and onions are golden. Let cool.
Place biscuit mix in large bowl; make well in center. Add water, remaining 1-1/2 tablespoons oil and onion mixture to well; stir just until combined.
Drop dough onto ungreased baking sheet into 8 equal mounds. Place a walnut half on each wedge. Or pat dough out onto floured foil to 9-inch round; cut into 8 equal wedges, but do not separate. Transfer to baking sheet; place walnut half in each wedge.
Bake in 425 degree oven for 15 minutes or until wooden pick inserted in centers comes out clean. Serve warm. Makes 8 biscuits.