For this dish I like to pick the zucchini blossoms at the end of the day when they have closed up but before the tips of the flowers have started to twist around, it makes them easier to fill without having the filling ooze out. Even blossoms that are a day old are ok if you can untwist the tips of the petals to push the tip of the pastry bag into the blossom. I don't remove the pistils or stamens from the blossoms but I do check inside to be sure there aren't any trapped insects. I usually have to collect blossoms for 2 to 4 days to get enough and have found that they keep well for a few days in the refrigerator in a large sealed container or a large bowl covered with plastic wrap. Plastic bags don't work as well, the blossoms get too battered.
If you have an aversion to using a pastry bag and have to use a spoon to fill the blossoms then you should pick the blossoms before they close up or you will have one huge exercise in frustration trying to stuff the blossoms. Try to twist the ends of the blossoms together so that the filling doesn't ooze out. That's a bit frustrating too, really, just try the pastry bag. I use a lightweight plastic pastry bag (Magic Line 14") which hasn't had the tip trimmed to fit a metal tip (no metal tip required for this recipe).
The stuffed blossoms are wonderful as an appetizer for 4 to 6 people or for a meatless main course for 2 or 3 people (2 if my husband is at the table).
6 tablespoons butter
1/4 ounce fresh sage leaves (about 24)
8 ounces whole milk ricotta (drain on paper towels if very wet)
1 1/2 ounces grated parmigiano
1 tablespoon whole wheat pastry flour or unbleached all purpose flour
1 large egg
1/2 teaspoon kosher salt
a generous grating of fresh nutmeg
8 to 12 zucchini blossoms, depending on size
Freshly ground black pepper
Preheat the oven to 350F.
Melt the butter over low heat in a flame proof baking dish or oven proof skillet. Add the fresh sage leaves to the pan, turn the heat up to medium-low and cook until the butter solids turn brown and the sage leaves crisp. Remove the pan from the heat. Remove the sage leaves from the pan and set them aside on a dish to cool. When cool, set aside 8 to 12 large whole leaves and chop the rest.
Mix together the ricotta, parmigiano, flour, egg, salt, nutmeg and chopped sage leaves. Spoon the mixture into a pastry bag. Stuff each blossom by pushing the tip of the pastry bag into the blossom and gently squeezing in enough to fill the bottom of the blossom (up to the point just below where the petals separate out into points). Lay each blossom in the baking dish and turn each blossom a couple of times to coat them a bit with the browned butter. Grind some fresh black pepper over all the blossoms.
So, here's the iffy part of the instructions, I haven't kept track of the time that the blossoms have been spending in the oven, but if memory serves me right (not always though), it should take about 20 to 25 minutes total. After about 15 minutes in the oven turn each blossom over so that it gets nicely coated with all that yummy butter and place one of the reserved sage leaves on top of blossom. Continue baking until the blossoms have puffed up and the ricotta filling has firmed up. Serve hot or warm.