If using frozen rolls, bake according to package directions. If using fresh soft rolls, slightly toast them. Bake enough rolls that will comfortably fit in your dish when they are cut into 1 inch pieces.
Make icing by combining powdered sugar with lemon juice or cream, adjusting amounts until you get the right consistency, and drizzle over rolls. Let rolls cool and then cut them into 1" pieces
Put cut roll pieces into a greased deep dish pie or quiche dish and sprinkle with blueberries
Whisk egg yolks 1-2 minutes, then add cream, sugar and salt, and stir to combine thoroughly
Add egg whites, vanilla, lemon juice and zest to yolk mixture
Pour mixture over roll pieces in dish and push down roll pieces to submerge if necessary
Slice butter into thin pieces and place all over top of rolls.
Cover and refrigerate for 8 hours or overnight so rolls can absorb custard
Uncover rolls and bake at 350 degrees for 45 minutes, check rolls and cover with foil if top is getting too brown. Continue baking for 10-15 more minutes or until set in the middle.
Let pudding sit for 5-10 minutes to set before serving