Preheat oven to 350°F, line 9x13-inch pan with parchment with overhang
Whisk flour, powdered sugar, salt in bowl
Cut in cold butter until mixture resembles coarse crumbs
Press firmly into prepared pan
Bake 18-20 minutes until edges lightly golden
While crust bakes, whisk eggs and sugar until combined
Add flour, lemon zest, lemon juice, salt, baking powder, whisk smooth
Pour filling over hot crust immediately
Bake 20-25 minutes until set and doesn't jiggle
Cool completely in pan, 1-2 hours
Increase oven to 375°F
Toss coconut with melted butter, honey, salt
Spread on baking sheet, bake 5-8 minutes, stirring every 2 minutes, until golden
Let coconut cool completely
Once bars completely cool, sprinkle toasted coconut over top, press gently
Refrigerate at least 30 minutes
Lift from pan using parchment, cut into 16 bars
Wipe knife between cuts
Dust with powdered sugar if desired
Serve chilled or room temperature