Thaw spinach and drain well, pressing between paper towels to remove excess moisture.

Prepare grits according to package directions.

In a large bowl, combine cooked grits, crumbled feta cheese, chopped green onions, chopped fresh basil, pressed garlic cloves, fresh lemon juice, salt, freshly ground pepper, and drained spinach. Mix well to combine.

In a separate bowl, stir together panko breadcrumbs, grated Parmesan cheese, and chopped fresh parsley.

Grease a 13x9 inch baking dish with vegetable cooking spray.

Sprinkle half of the panko mixture into the prepared baking dish, ensuring an even layer.

Pour the hot grits mixture into the baking dish, spreading it evenly over the panko layer.

Sprinkle the remaining panko mixture over the grits.

Cover the baking dish with plastic wrap or foil and chill in the refrigerator for at least 8 hours.

After chilling, invert the grits onto a cutting board.

Cut the grits into 24 squares, then cut each square diagonally to form two triangles.

Preheat a griddle or nonstick skillet over medium heat and grease with vegetable cooking spray.

Coat both sides of each triangle with cooking spray.

Cook the triangles in batches on the hot griddle or skillet for 2 minutes per side, or until golden brown.

Place the cooked triangles on a wire rack on a baking sheet to keep warm.

Keep the triangles warm in a 200°F (93°C) oven for up to 30 minutes before serving.