In a skillet over medium high heat, melt 1 tbsp of butter and add onions. Sauté for 3-4 minutes or until they start to soften. Remove to a plate.
Spread one side of all 4 slices of bread with butter. Flip over and for each sandwich, spread one side with cream cheese and the other slice with goat cheese. Top the goat cheese side with strawberries and onion. Drizzle balsamic glaze. Top the cream cheese side with turkey and bacon, then sandwich the 2 halves together.
Grill the sandwiches in a non-stick pan over medium heat until golden brown on each side – about 2-3 minutes each. Remove from heat and then finish each sandwich with arugula inside. Serve warm.