Preheat oven to 400°F (200°C). Line two baking sheets with parchment paper.

In a medium saucepan, combine water, milk, butter, sugar, and salt. Bring to a rolling boil over medium heat, stirring occasionally to melt the butter.

Once boiling, remove the saucepan from heat and immediately add the sifted flour all at once. Stir vigorously with a wooden spoon or spatula until the mixture forms a ball and pulls away from the sides of the pan.

Return the saucepan to low heat and continue to cook for 1-2 minutes, stirring constantly, to dry out the dough. A thin film will form on the bottom of the pan.

Transfer the dough to the bowl of a stand mixer fitted with the paddle attachment (or a large mixing bowl). Let it cool for 5 minutes, stirring occasionally, until it's warm but not hot to the touch.

With the mixer on medium-low speed, add the eggs one at a time, incorporating each egg fully before adding the next. Scrape down the sides of the bowl as needed. The dough will look curdled at first but will come together into a smooth, glossy, pipeable consistency. It should be thick enough to hold its shape but soft enough to pipe.

Transfer the choux pastry to a piping bag fitted with a large round or star tip. Pipe 12-14 mounds, about 1.5-2 inches in diameter, onto the prepared baking sheets, leaving about 2 inches between them.

Bake for 20 minutes at 400°F (200°C), then reduce the oven temperature to 350°F (175°C) and bake for an additional 15-20 minutes, or until the puffs are golden brown, puffed, and firm. Do not open the oven door during the first 20 minutes of baking.

Turn off the oven, leave the door slightly ajar, and let the cream puffs cool in the oven for 15-20 minutes. This helps prevent them from deflating.

Remove from the oven and transfer to a wire rack to cool completely.

In a large mixing bowl, using a hand mixer or stand mixer with a whisk attachment, beat the softened cream cheese until smooth and creamy.

Add the powdered sugar and vanilla extract, beating until well combined and fluffy.

In a separate cold bowl, whip the cold heavy cream until stiff peaks form.

Gently fold the whipped cream into the cream cheese mixture until just combined.

Fold in the finely diced strawberries. Refrigerate until ready to fill the puffs.

Once the choux pastry shells are completely cool, slice each puff horizontally using a serrated knife, almost all the way through, creating a "hinge," or slice completely in half.

Spoon or pipe the strawberry cream filling generously into the bottom half of each puff.

Replace the top half of the choux pastry.

If desired, whip the extra heavy cream with powdered sugar and vanilla extract until stiff peaks form. Pipe a small dollop of whipped cream on top of each filled puff.

Garnish with fresh strawberry slices. Serve immediately or refrigerate until serving.