Lightly toast then cool nuts; chop until very fine and set aside ~ If using a food processor for chopping, allow nuts to cool very thoroughly before chopping them in order to avoid turning them into a paste.
Cream butter and sugar for 3-4 minutes in a stand mixer fitted with paddle attachment until extra light-colored and fluffy; stir in vanilla.
Whisk together dry ingredients; add gradually to butter mixture, stirring just until (do not overmix) dough comes together; stir in chopped nuts.
Chill dough if it seems too soft.
Form dough into 1 1/4" balls and place onto parchment-lined or ungreased baking sheets; indent the top of each ball of dough with your fingertip or with the dampened end of a wooden spoon.
Bake at 325° for 10-12 minutes or just until the cookies start to turn light golden-brown at the edges; remove from oven and sprinkle lightly with powdered sugar; fill each indentation with a bit of jam or fruit preserves ~ I like to use red raspberry preserves.
NOTES: Yield becomes 60 cookies when dough is formed into 1" dough balls. And any type of toasted and chopped nuts may be substituted for the almonds.