Heat oven to 425°F. Attach a deep-fry thermometer to a small pot, add canola oil and heat to 350°F. In a food processor, pulse garlic, yellow onion and 1/2 cup spinach until very finely chopped. Add chickpeas, flour, cumin, coriander and 1/2 teaspoon salt and pulse to combine (chickpeas should be chopped but coarse). Form mixture into 2-Tbsp balls and fry in batches until golden brown, turning as necessary, 4 minutes. (Note: Oil must remain between 340°F and 360°F or balls will fall apart; adjust heat as needed.) In a food processor, pulse baguette to form coarse crumbs; transfer to baking sheet and toast until dry and crisp, 5 to 7 minutes. Meanwhile, in a medium bowl, combine tomatoes, red onion, lemon juice, olive oil, 1/4 teaspoon salt and 1/2 teaspoon pepper. Finely chop remaining 4 cups spinach and fold into salad. Top with crumbs and serve with falafel.