Top each cookie with some jam. (You can skip the jam, but see note that follows.)
In a medium bowl, beat the cream cheese with electric mixer until it is fluffy. Add the sweetened condensed milk and mix again. Then add the eggs and mix for 2-3 minutes.
Divide the batter among the 12 cups. The cheesecake will not expand as it cooks, so you can fill the papers all the way to the top and don't worry about them overflowing in the oven. In my photos, you'll see I filled mine just a bit low. Next time I would fill a bit higher.
I found I had batter left over for 3 more cheesecakes. So, I made 3 without jam. Those became upside-down cheesecakes, because the cookie crust rose to the top. (See photo below).
Bake the cheesecakes for 20 minutes. Remove from oven and cool in the muffin pan for about 20 minutes, then set the muffin pan in the fridge for about an hour or until ready to serve. Here is a photo of them just out of the oven. The ones on the right were baked without jam, and the cookie bottoms rose to the top.
Heat up some jam in the microwave and put a little on top of each cheesecake before serving.
I found that after removing the paper, the cheesecake could be held in your hand and eaten, if desired.