Line with parchment paper a loaf pan and leave an overhang on long sides; spray parchment.
Bring dates and maple syrup to a boil in a small saucepan, reduce heat when dates are very soft and maple syrup is slightly reduced, 8–10 minutes.
Remove date mixture from heat and stir in butter until it is melted.
Mash dates with a potato masher or fork.
Toss oats, almonds, pumpkin seeds, sunflower seeds, and salt in a large bowl.
Mix in date mixture until evenly coated.
Scrape half of oat mixture into prepared pan and press very firmly down to the pan with the back of a large spoon.
Add remaining oat mixture and press until very tightly packed into pan.
Bake, until top is brown and firm around the edges.
Transfer pan to a wire rack and let loaf cool in pan.
Cut into ½ thick slices with a serrated knife.
For crisper bars, lay slices on a baking sheet for another 5 minutes.