Soft and chewy vegan thumbprint cookies with a smooth jam center. Use a jam of your choosing to fill the cookies, or make a quick-setting jam using agar powder (recipe below).
Preheat the oven to 350 degrees Fahrenheit. Line two baking sheets with parchment paper. If needed, melt your coconut oil and then allow it to cool for a few minutes (we don't want it to be hot when mixing the cookie dough).
In a large mixing bowl, beat together the coconut oil and sugar for about a minute until combined. Add the non-dairy milk, vanilla extract, and lemon zest, and mix for another minute or so, or until the texture looks like applesauce.
Add half of the flour, the cornstarch, baking powder, and salt, and mix well until combined. Add the other half of the flour and mix until a smooth, soft dough forms.
Use a cookie scoop if you have it, or a rounded 1tbsp measurement to measure the cookies and roll them into balls. Flatten each ball slightly on the baking sheet, and then use a measuring spoon or your thumb to press an indentation into the dough.
Bake for about 11 minutes, or until the bottoms of the cookies are golden. Remove from the oven and let cool for a few minutes before removing from the baking sheet to cool completely before filling.
For the lemon (or other fruit flavor) filling:
When you're ready to fill the cookies, add all of the filling ingredients to a small saucepan and stir well to dissolve the cornstarch. Bring to a boil, stirring frequently. Cook for 1 more minute while continuously stirring, then immediately remove from the heat and spoon into the centers of the cookies. It will start to solidify within minutes.
Notes
FLAVOR VARIATIONS: Swap in any other citrus fruit and its zest for the lemon to vary the flavors in the cookies (you can also use different zest or omit the zest in the dough, although I've found that the lemon zest pairs well with everything). Any other type of fruit juice can also be used in place of the lemon; simply omit the zest and swap the juice 1:1. The cookies pictured in my photos are half lemon, half black cherry juice.