I used a blender to puree the fennel, onion, and apple, but I think a good variation on this would be to simply sqeeze lemon over them, splash on a little white wine, toss, and put them on the pizza as a topping. —clintonhillbilly
Combine ricotta with honey, lemon zest, 1 tbsp lemon juice, and chopped thyme.
Heat grill to high. Place fennel slices and 1/2 onion on grill. Do not slice the onion. Don't worry if you lose a few fennel slices through the grate. When they are browned, flip them. Tongs are easier than a spatula so that you can place them back on the grate without losing them.
Remove onion and fennel from grill and chop.
Combine diced apples. pine nuts, and chopped fennel and onion in a bowl or in a blender.
If using as a topping, splash on a little white wine vinegar squeeze half a lemon over mixture, grind on some black pepper, and toss. If making a sauce, puree, adding a little water.
Roll out pizza dough and oil both sides with olive oil. Place on grill and flip after 1-2 minutes.
Remove from grill and top with ricotta and fennel topping to taste. Place back on the grill for a minute or two if desired.