Preheat oven to 350F
Grease shallow 2qt baking dish with butter
Cover the bottom of the baking dish with a layer of fennel slices. Cover with 1/2 the potato slices. Sprinkle with salt & pepper & herbs to taste. Repeat layers until slices are used up.
Bring the half-and-half to a gentle boil in a medium pan over med-high heat. Pour it over the fennel & potato
Using a large spatula, ress down on the top layer to submerge it. Dot with butter. Bake until potatoes are tender & top is golden, ~1hr.
If using cheese, sprinkle it on, grated, for the last 15 mins of baking - brown under the broiler at the very end if it's not golden yet!
Note: this dish can also be made entirely in a cast iron skilled - panfry the fennel & potatoes in butter until somewhat softened. Add the cream then pop into the oven to complete the cooking process.