In large pot, boil potatoes in their jackets for 10 minutes, then add cauliflower florets and cook until a fork pierces potatoes easily and cauliflower is quite soft, about 5 minutes depending on size of potatoes. Drain well and let cool.

In large skillet, heat oil or butter over medium heat. Add bread and stir until toasted and golden. Remove to medium bowl. To the pan, add spinach along with 1/4 tsp salt and pepper and cook for 30 seconds, until wilted. Transfer to bowl with bread and stir in 1 Tbsp minced parsley.

Peel potatoes and press through potato ricer or the largest side of box grater into large bowl. Repeat with cauliflower. Stir together grated potatoes, cauliflower, starch, ground chia seeds or egg, nutmeg, and remaining 1 tsp salt and 1/4 tsp pepper. Let rest for 10 minutes if using chia seeds.

Divide dough into 12 tightly shaped balls. Press your thumb into each ball and add a crouton and some spinach. (Do not overstuff your dumplings or they might fall apart.) Cover filling with dumpling dough to seal.

Bring large pot of water to a boil. Reduce heat to medium-low (don’t keep it at a boil or dumplings will fall apart) and add half the dumplings. Once they rise to the top of the boiling water, cook for 5 minutes. With slotted spoon, remove dumplings to plate and repeat with remaining balls.

Sprinkle with remaining parsley and serve with sliced radishes or mushroom sauce.