Combine the sliced strawberries, 3 tablespoons sugar, lemon juice, and vanilla extract in a saucepan over medium-high heat. Bring to a boil and let it bubble for 2-3 minutes, stirring occasionally to break down the berries slightly. Then reduce the heat to low and simmer for 20-25 minutes until the syrup thickens and deepens in color. This can simmer while you prepare and cook the pancakes, so start this first to maximize your time.
While the syrup simmers, cut the cream cheese into small 1/4-inch cubes and set aside on a plate—I find it helpful to chill the cream cheese for a few minutes so the cubes hold their shape better when they hit the hot pancake. In a large bowl, whisk together the flour, 4 tablespoons sugar, baking powder, baking soda, and salt. In a separate small bowl, whisk together the room-temperature egg, buttermilk, and melted butter until well combined. Pour the wet ingredients into the dry ingredients and stir just until combined—don't overmix, as lumps in the batter will create fluffier pancakes.
Heat a griddle or large skillet over medium heat and lightly butter it. Pour about 1/4 cup of batter onto the hot surface, then immediately sprinkle 3-4 cream cheese cubes onto the center of the pancake, followed by 2-3 strawberry slices. Gently press them into the batter slightly so they stay embedded. Cook until bubbles form across the top and the edges begin to brown (about 2-3 minutes), then carefully flip and cook the other side until golden brown (about 1-2 minutes). I like to use a thin spatula to ensure a clean flip without disturbing the delicate cheese and fruit inside.
Transfer each finished pancake to a serving plate and generously drizzle with the warm strawberry syrup from Step 1. Add whipped cream on top if desired. Repeat the cooking process with the remaining batter until all pancakes are made, keeping finished pancakes warm on a plate in a 200°F oven if needed.