How to use fennel fronds?

Fennel fronds are wildly used in (south) Italian cooking, or to be exact: finocchietto, a wild variety consisting of mostly fronds – since it’s hard to find those outside Italy, finding an extra frond-y fennel always feels like a jackpot to me :)
Anyways: searching for finocchietto will give you an idea for its different uses and recipes.
A sicilian classic, and my favourite, is pasta con le sarde, for which there are various recipes on this site (using canned or fresh sardines, with or without tomato, pine nuts and raisins or not, …) For me the only non-negotionable component is the crunchy seasoned breadcrumb topping.

I like to make a fennel and charred blood orange salad (blow torch baby) and the sprinkle the fronds over. Good with grapefruit too.

Taken in part from a food52 article: Fronds
Chop up the fronds and use them like you would other fresh herbs. They're lovely in a pesto, an egg or potato salad, or as a garnish, like on this soup.

I dry them and throw them into tomato sauce and bolognese, as well as salads and stews. They're really adaptable for someone who likes the anise flavor -- drying them will increase their shelf life so you can use them at will!

I snip them with scissors for use as a garnish. If you don't think you'll use them all, I'm sure you could infuse some olive oil with them but I've never actually done that with fennel myself.