Add the dulce de leche and butter to a bowl. Microwave for about 30 seconds until butter melts. Mix until incorporated. Set aside.
In a bowl, beat the eggs for a couple of minutes until they begin to fluff. This can be done by hand or beater.
Add the dulce de leche mixture little by little to the egg. Mix until incorporated.
Add flour (sift it through a sieve) and add it little by little. Fold in.
Grease 4 ramekin molds with butter and flour. You can use the 7 oz (207 ml) round CorningWare French White ramekin.
Place the stainless steel inner pot inside the Instant Pot®, add 1 cup of water, the rack, and place the molds on it. You can do this in batches or put them on top of each other (depending on the size of your pot).
Close and lock the Instant Pot® lid. Make sure the steam release handle is turned to Sealing. Press Pressure Cook, pressure level HIGH, and set time to 8 Minutes.. But if you have larger or thicker molds, set to 10 Minutes.
Once the time is up, turn the valve to Venting and, when it stops releasing steam, press Cancel.
Open and carefully remove the molds. Leave for a couple of minutes and with a knife, carefully cut around the edges.
Place a plate on top of the mold, turn the plate over, and carefully unmold.
Serve with vanilla ice cream, powdered sugar, etc.