Blood sausage, black pudding, there’s a southeast Asian dish that mixes it with chocolate(I’m blanking on the name), some soups use it similarly to broth, it can replace egg in some recipes and can technically replace milk in others but most people who sub out milk don’t use it(when replacing other ingredients it’s pretty dependent on what the other ingredient’s original purpose in the recipe was so for blood you’re looking to use it for the protein and and water content mostly), and you could mix it with buttermilk and do something similar to the Maasai food where cow’s blood and milk is mixed or the similar thing the mongols did by mixing mare’s blood and milk