Place the rack in the center and preheat your oven to 350°F. Cover 2 cookie sheets with parchment paper or silicone mats.
In a bowl, cream together the butter and sugar, then add the eggs and sea buckthorn juice.
Once well mixed, add the flour, salt, oat flakes, baking powder and sea buckthorn powder. Mix well.
For more decadence, you can add chocolate chips.
Using spoons, form balls of dough and distribute them on the baking sheets, spacing them apart.
Using a sieve, sprinkle the sea buckthorn powder on top of the biscuits before putting them in the oven.
Bake for 8 to 12 minutes, or until lightly golden. Serve warm or cold.