Preheat oven to 350 degrees F and line a baking sheet with a silicone baking mat or eco-friendly parchment paper.
Make chia egg. In a medium bowl, combine 1 tablespoon chia seeds and 3 tablespoons room temperature water to make a chia egg. Let sit for 5-7 minutes to allow the mixture to thicken (it will become your egg-free binder).
Grind oats and sunflower seeds. While the chia-water mixture is thickening, add sunflower seeds and oats to a food processor or blender. Pulse until it forms a fairly fine flour. Don’t worry if there are still larger pieces though. Add cornstarch, baking powder and salt to the food processor and pulse a couple times to incorporate these ingredients.
Combine ingredients. Once the chia egg has thickened, add maple syrup, vanilla and coconut oil to the bowl with the chia egg. Stir to combine. Then add the dry ingredients to the bowl of wet ingredients and stir to combine. Feel free to use your hands to combine everything together. The cookie batter should be thick and hold together well, it shouldn’t be runny. If needed add a bit more oats or water until it reaches the desired consistency.
Spoon batter. Using a cookie scoop or spoon, form about 2 tablespoons of cookie dough into a ball and place on a lined cookie sheet about 1 inch apart. If you find the dough to be too sticky to roll into balls, place it in the fridge for about 10 minutes to let it firm up a bit. Using your thumb or the back of a teaspoon, make an indentation in the center of the cookie dough. Repeat until all the dough has been used.
Bake the cookies for about 15 minutes or until the edges begin to brown and the cookies are firm. I like to slightly under-bake them so they’re a little softer. Then remove from the oven and let cool. Spoon jam into each thumbprint, filling the indent to the brim. Enjoy!
PREP AHEAD: These cookies can be prepared in advance and stored for four days (or longer in the fridge or freezer). You can also prepare the batter up to two days ahead of time and then bake. LEFTOVERS/STORAGE: store cookies in an airtight glass container either in the fridge or at room temperature for up to four daysNUTRITION NOTES: these "healthier" plant-based sunflower thumbprint cookies use chia seeds instead of an egg for a binder and sunflower seeds and oats instead of regular flour. They are vegan, gluten-free and are lower in sugar than other cookie recipes.This recipe is adapted from Green Kitchen Stories Jam & Sunflower Thimble Cookies