Meanings of add a tsp in English

Flatten each ball of dough out and add a tsp of the garlic and onion butter.

Flatten each ball of dough out and add a tsp of the garlic and parsley butter.

Have boiling water, add a tsp.

(When cream is not available use the same quantity of milk, previously thickened to the consistency of cream with a little cornstarch, add a tsp.