1. Combine 1 tbsp of the oil (for 4 servings), rosemary, and pressed garlic in a small bowl, microwave on high 1 minute. Place rosemary mixture, lemon juice, beans, salt and black pepper in food processor. Pulse until a coarse paste forms, scraping down sides of bowl as necessary.
2. To assemble panini, brush one side of each bread slice with remaining oil; place bread oil side down on cutting board. Spread 2 tbsp of the bean mixture over each bread slice; sprinkle with cheese, pressing down firmly. Arrange tomato slices, onion and arugula over half of the bread slices; top with remaining bread slices, oil side up.
3. Heat grill pan or griddle over medium heat. Cook panini 2-3 minutes per side or until grill marks appear and bread is golden brown. Cook in batches if needed. Slice panini in half crosswise; serve immediately.