In a stand mixer or with a hand mixer, cream together the butter and sugar until light and fluffy.
Beat in the ricotta, scraping down the bowl and ensuring that it is incorporated fully. Do the same with the egg and vanilla.
Whisk together the flour, baking powder and salt. Gradually mix the dry into the batter, using a low speed and being sure not to overmix. The dough should be fluffy but not too airy.
Scoop the dough by tablespoons onto parchment- or silicone-lined sheet pans. The cookies should be about 2" apart and you should be able to get about 12 on each sheet. Bake for about 15 minutes, until lightly browned on the bottom.
Once you've removed the cookies from the oven, wait 30-60 seconds, then make an indentation with your thumb in the middle of each one. Move the cookies to a wire rack to finish cooling.
Fill the middle of each cookie with a scant teaspoon of jam, then drizzle very lightly with honey and sprinkle with nuts.