Heat 1 tablespoon butter and 1 tablespoon olive oil in large skillet over medium-high heat. Add summer squash; cook over medium-high heat 2 to 3 minutes or until golden brown and crisp-tender. Remove from skillet; set aside. For garnish, add lemon slices to skillet; sear 1 minute or until lightly charred on both sides; remove from skillet and set aside.

Add remaining 1 tablespoon butter and 1 tablespoon olive oil to skillet; reducing heat to medium-low. Add shallot and garlic; cook 2 to 3 minutes or until softened, stirring occasionally.

Add uncooked orzo to shallot mixture; stir to coat. Stir in vinegar; cook and stir until liquid is absorbed. Add broth; bring to a boil. Reduce heat; gently simmer, uncovered, 10 to 12 minutes or until orzo is al dente and most of the liquid is absorbed.

Pat shrimp dry with paper towels. Add shrimp, spinach, salt, and pepper; stir to combine. Cook 1 to 2 minutes or until shrimp reach 145° and spinach is wilted, stirring often. Add squash; stir in lemon zest and juice. Remove from heat. Garnish with charred lemon slices and fresh dill, if desired.