• Measure the flour and set aside.
• In a large sauce pan, combine the flour, milk, butter, sugar and salt. Bring the mixture to a full boil over medium heat. Add the flour all at once. Stir with a wooden spoon until smooth. Continue stirring until the dough appears dry and does not cling to the pan sides or the spoon. Do not over stir at this point or the dough may not puff when baked. Transfer to a bowl and let cool for 5 minutes, stirring occasionally. This is important so that the eggs don't prematurely.
• Using a mixer, add eggs, one at a time, making sure dough is smooth before adding the next egg. Refrigerate paste up to 4 hours or use immediately. You do not need to bring the paste to room temperature to shape.
• Position a rack in the lower ⅓ of the oven. Preheat the oven to 400°F.
• Scoop the paste into a pastry bag and use a ½ inch tip or a freezer bag and cur the corner off about ½ inch. squeeze into 2½ to 3 inch mounds about 1 inch high, onto a ungreased baking sheet. If desired, dampen a pastry brush and smooth the puffs. I often use a tip with small ridges for texture.
• Bake for 10 minutes, then reduce the oven to 350°F and bake until golden brown and firm to the touch, about 25 minutes more. Remove to a rack and let cool completely.

For the filling

• Pour the half and half into a medium heavy bottomed saucepan. Add the ½ cup of sugar and salt. Bring the mixture to a simmer on medium low heat, just until the sugar dissolves and you see tiny bubbles begin to appear on the surface of the half and half. Meanwhile, whisk the egg yolks with the remaining 2 Tablespoons of sugar in a medium bowl, until the sugar dissolves. Add the cornstarch and keep whisking until it's completely incorporated into the egg yolks.
• As soon as the half and half comes to a simmer, ladle in a small amount of the hot liquid into the egg yolk mixture, whisking it all together at the same time, to make sure your eggs don't scramble. Gradually add more of the hot liquid, until it is all of it mixed together. Pour the mixture back into the saucepan, return it to the stove and cook on low heat, whisking constantly, until the pastry cream thickens. Remove from heat and add the butter and vanilla.
• Cool the pastry cream before using it, you can make the pastry cream in advance. Keep it refrigerated and tightly covered. To prevent a skin from forming on the very top of the pastry cream, place a piece of plastic wrap or a bit or parchment paper directly on the surface of the pastry cream.

Assemble the puffs

• Slice the tops from the puffs and remove any uncooked paste.
• Save about 1 cup of the whipped cream to top off the puffs.
• Fold remaining cold sweetened whipped cream into the pastry cream. Amount depends on how many puffs you are filling, using about half, if you are only filling half of your puffs at this time.
• Peel and slice your bananas. Using ½ of a banana for each puff.
• Place a generous spoonful of pastry cream mixture in the bottom of each puff, a few slices of banana and another big spoonful of the pastry cream mixture over the bananas. Place a few more slices of banana and top with a spoonful the plain sweetened whipped cream over the top of that. Place the puff tops over all, set slightly askew. Dust powdered sugar, if desired. Serve refrigerated or at room temperature if eating as soon as you put them together.