Using a large pot, bring water to a boil, then add spinach.
Cook until they become soft --- drain, then place in icy water for about 3 minutes.
Drain and use your hands to squeeze the remaining liquid out of the leaves; then set aside.
Using a medium or large pot, melt the butter over medium heat.
Once the butter has completely melted, add the flour.
Mix until it turns darker in color.
Add the chopped shallots and mix and cook until they become soft.
Pour the stock and mix with a whisk to make sure there are no lumps.
Cover with a lid and bring to a boil.
Add the cream and the drained (and squeezed) spinach, then mix.
Remove the pot of soup from the heat.
Use an immersion blender to puree the soup to your desired texture.
Place the pot back into the heat and season with salt and pepper.
Mix, cover with a lid, and bring to a boil.
Your Finnish spinach soup is now ready for serving!