Preheat oven to 425°F. Unroll pastry and place side by side (overlapping slightly to form pizza crust) to fit on a large parchment-lined baking sheet. Press overlapped dough together so it sticks. Prick all over with a fork. Fold and press ½ inch (1 cm) of pastry all around outside edge to form a rim. Refrigerate until ready to use.
Using your hands, over the sink, squeeze out excess water from shrimp and scallops. Place in paper towel then gently squeeze again.
Melt butter in a medium saucepan over medium heat. Add garlic; cook 1 min. Sprinkle with flour, thyme and salt; whisk. Gradually whisk in milk. Bring to a boil, then reduce heat, whisking for 2 min or until smooth and thickened. Turn into a bowl and refrigerate.
Slice salmon crosswise. Chop red pepper into ½-inch (1 cm) pieces. Remove pastry from fridge. Thinly spread with milk sauce. Sprinkle with half the Mozzarella. Scatter with red pepper and onion. Add shrimp, scallops, smoked salmon and remaining cheese.
Bake 18 min or until a deep golden brown. Let stand for 5 min before slicing. Garnish with microgreens.
Notes
It is really important to remove all moisture from seafood or pizza will be soggy.