Preheat your oven to 350° F. Line a muffin tray with muffin liners or grease each hole with coconut oil.
In a high-speed blender, add all ingredients except pumpkin seeds, almonds and frozen blueberries. Start with the wet ingredients, then add the dry. Blend for 30 seconds to one minute, or until smooth.
Once batter is smooth, fold in pumpkin seeds, almonds and blueberries.
Scoop out batter into the muffin tray and fill each about 3/4 of the way full. Bake for 25-30 minutes until golden brown on top. Let the muffins cool while you prepare the elderberry jam filling.
Add frozen berries to a saucepan over medium heat and stir a few minutes while the berries thaw. When thawed and warm, mash berries with a fork, then add all other ingredients, stir together and remove from heat. Let this sit for 5 minutes to let the chia seeds gelatinize.
Using the thick end of a chopstick, poke holes in each muffin top and use the chopstick to create space in the middle of the muffin, where the filling will go.
Add elderberry filling to a piping bag or a plastic bag* and cut a small hole in the bottom corner of the bag. Insert this open corner into each muffin and apply pressure to the bag until filling comes out the top of each muffin.