When you measure out the spinach make sure to remove the stems and make sure the leaves are dry.
Blanch the spinach uncovered for a few minutes and then plop it in an ice bath or under really cold water until cool. The leaves should be soft. Squeeze out as much liquid as you can or it will water down your beautiful creation. Also covering it while it cooks will ruin some of the color due to an amino acid.
Start your roux (flour+fat). Melt the butter and add the flour to it until it barely turns brown.
Add the shallots and stir
Add a pinch of salt
Add the chicken stock and bring everything to a boil for 2 minutes
Add the cream and let it bubble for 30 seconds while stirring in the dill
Add the spinach for 30 seconds
Take everything into a large CuisinArt (or work in batches) and puree.
At this point while it is still hot in the CuisinArt, add a pinch of salt. Taste it. Good? No? Add a pinch more. This is cooking 101.
You done done it! Enjoy.