In a large pot, toast fennel seeds for a minute or two on medium low heat until fragrant.
Combine all the other ingredients and mix well. Turn up heat and bring to a gentle boil, then reduce heat to a simmer. Cook for at least 45 minutes while stirring occasionally.
Sauce can be used right away for pizza, or if not, store in freezer in airtight in a glass canning jar. (I’d recommend trying to use the remaining sauce within one month of freezing.)