2.In a large saucepan, bring the water to a boil; gradually whisk in polenta. Reduce heat; simmer, whisking, for about 5 minutes or until mixture thickens. Stir in cheese.
3.Smooth polenta mixture in prepared pan (see notes). Cover; refrigerate for about 3 hours or until firm.
4.Turn polenta onto a chopping board; cut polenta in half. Cut each half into quarters; cut each quarter in half diagonally.
5.In a medium saucepan, heat oil; cook onion and garlic, stirring, for about 2 minutes or until onion is soft. Add tomatoes, stock, paste and chilli; bring to a boil. Reduce heat; simmer, uncovered, for about 5 minutes, or until thickened slightly.
6.Add beans, spinach and basil; cook, uncovered, for about 3 minutes, or until spinach is wilted and beans are hot.
7.Just before serving, cook polenta, in batches, on a large, heated dry grill plate (or grill or barbecue) for about 3 minutes or until browned both sides; drain on paper towel. Serve with tomato bean mixture.
Any kind of dried beans can be substituted for canned beans, if preferred. Soak beans overnight. Boil until tender; drain. Use patience when spreading polenta into prepared pan; it tends to move and slip but can eventually be worked into corners of pan. Polenta can be made 1 day ahead to the refrigeration stage.