Heat olive oil in skillet set over medium heat; cook onion and minced garlic for about 5 minutes or until softened. Stir in palmitos; cook for about 2 minutes or until well coated. Stir in tomato paste; cook for 1 minute. Sprinkle flour over top; cook for about 2 minutes or until smooth.
Slowly whisk in milk; bring to boil, whisking constantly. Stir in chicken and Adobo. Reduce heat to medium-low; cook, stirring constantly, for 2 to 5 minutes or until thickened. Remove from heat. Let cool completely. Stir in hard-boiled eggs and small pitted ripe black olives.
Preheat oven to 400˚F. Whisk egg with 1 tbsp. water; brush some of the egg wash lightly onto edges of half of the discos. Fit each pastry into mini muffin cups, pressing into bottom and up side of cups.
Divide filling among pastries. Cap with remaining discos, pinching to seal edges together. Brush tops with remaining egg wash. Prick top of pastry with fork for vents. Bake for 18 to 25 minutes or until pastry is golden brown.
Note: Add a little crumbled feta or shredded mozzarella cheese to filling if desired.