Preheat oven to 400°F and line a baking sheet with parchment paper.
Halve jalapeños lengthwise, then remove seeds and membranes using a small spoon; wear gloves to protect hands.
In a mixing bowl, combine softened cream cheese, mayonnaise, shredded cheddar cheese, green onions, garlic, parsley, lemon zest, Cajun seasoning, smoked paprika, salt, and black pepper; mix well.
Carefully fold in crabmeat until just combined, avoiding breaking up lumps.
Spoon the crab mixture evenly into each jalapeño half, mounding slightly.
Mix panko breadcrumbs with melted butter until crumbly and spread evenly over each filled popper.
Place poppers on prepared baking sheet and bake 18-20 minutes until golden brown.
Remove from oven and let cool for 5 minutes before serving.