Butter the sides of a heavy 2-quart saucepan. Add Splenda Sugar Blend, brown sugar, half-and-half, and milk. Cook over medium-high heat until mixture comes to a boil. Reduce heat to medium-low and cook, stirring frequently, until candy thermometer reaches 236°F or soft ball stage (15–20 minutes). Remove from heat. Add butter and vanilla extract; do not stir. Cool, without stirring, until mixture reaches 110°F.
Add pecans; beat with a wooden spoon or electric mixer fitted with paddle attachment until mixture thickens and just begins to lose its gloss.
Quickly pour into prepared pan and spread evenly. Use a sharp knife to score into squares. Cool completely; cut when firm.