In a large Dutch oven or heavy pot over medium heat, melt 3 tablespoons butter. Add panko and cook, stirring frequently, until toasted, about 4 minutes. Add one-quarter of garlic and cook, stirring, until fragrant, about 30 seconds. Put the bread crumb mixture into a bowl and mix in parsley and lemon zest; season with salt and pepper.
Wipe out the pot and return it to medium heat. Cook orzo and remaining garlic and 2 tablespoons butter, stirring occasionally, until orzo is lightly toasted and garlic is fragrant, about 4 minutes. Add broth, milk, and 1 cup water; season with salt and pepper. Increase heat to medium-high and bring to a boil. Reduce heat to medium-low and simmer, stirring frequently and adding more water by the tablespoon if the liquid is thickening too fast, until the liquid is mostly absorbed and orzo is tender, 10 to 12 minutes.
Add kale and Parmesan and stir until kale is wilted and cheese is combined and melted, about 2 minutes; season with salt and pepper.
Divide orzo mixture among plates. Top with bread crumbs and more Parmesan. Serve with lemon wedges alongside.